United States Congress elections, 2018
Four hundred and seventy seats in the U.S. Congress (35 Senate seats and all 435 House seats) were up for election on November 6, 2018.
The Republican Party held 51 seats in the Senate. Democrats held 47 seats, and the remaining two were held by independents who caucus with the Democratic Party. The Democratic Party faced greater partisan risk in 2018, as they were defending 25 seats (two of which were held by independents), while eight seats up for election in 2018 were held by Republican incumbents. The Democratic Party had to defend seats in 10 states that supported Donald Trump (R) over Hillary Clinton (D) in 2016.
Republicans also controlled the U.S. House of Representatives. As of October 2018, the Republican Party was in the majority, holding 235 seats to Democrats' 193 seats, with seven seats being vacant. The Democratic Party was well-positioned to gain seats in the chamber in 2018; since 1934, the party of a newly elected president has suffered an average loss of 23 seats in the House in the following midterm.[1]
Political observers discussed the possibility that 2018 would be a wave election against President Trump and the Republican Party. But what would have qualified as a wave election?
In a collaboration with political scientist Jacob Smith, Ballotpedia analyzed election data from 1918 to 2016 and defined wave elections as the 20 percent of elections in that period where the president's party lost the most seats. For the U.S. House and the U.S. Senate, this meant that Republicans would need to lose 48 House seats and seven Senate seats for 2018 to qualify historically as a wave election. Read the full report here.
Ballotpedia has compiled the following resources to help voters better understand the landscape and consequences of the midterm elections in 2018:
- An overview of recent presidential voting trends in states with Senate races and competitive districts;
- The battlegrounds in the U.S. Senate and U.S. House;
- Media coverage of the possible outcomes and consequences of these elections; and
- An overview of special elections in 2017 and 2018.
Battlegrounds
U.S. Senate
There were 24 Democratic seats, nine Republican seats, and two seats held by independents up for election in 2018; hence, the partisan risk for the Republican Party is low. In 2018, the Democratic Party needed to pick up two seats in the Senate in order to regain the majority they lost in 2014.[2]
The following map displays which Senate seats were up for election in 2018 and identifies those races that were considered battleground elections. Mouse over a state for more detailed information.
| Results of United States Senate battlegrounds, 2018 | ||||
|---|---|---|---|---|
| State | Incumbent | Winner | Partisan change | Incumbent status |
| Arizona |  Jeff Flake |
 Kyrsten Sinema |
Yes | Incumbent didn't seek re-election |
| California | Dianne Feinstein |
Dianne Feinstein |
No | Won |
| Florida | Bill Nelson |
Rick Scott |
Yes | Lost |
| Indiana | Joe Donnelly |
Mike Braun |
Yes | Lost |
| Minnesota (special) | Tina Smith |
Tina Smith |
No | Won |
| Missouri | Claire McCaskill |
Josh Hawley |
Yes | Lost |
| Mississippi (special) | Cindy Hyde-Smith |
Cindy Hyde-Smith |
No | Won |
| Montana | Jon Tester |
Jon Tester |
No | Won |
| North Dakota | Heidi Heitkamp |
Kevin Cramer |
Yes | Lost |
| New Jersey | Bob Menendez |
Bob Menendez |
No | Won |
| New Mexico | Martin Heinrich |
Martin Heinrich |
No | Won |
| Nevada | Dean Heller |
Jacky Rosen |
Yes | Lost |
| Ohio | Sherrod Brown |
Sherrod Brown |
No | Won |
| Tennessee | Bob Corker |
Marsha Blackburn |
No | Incumbent didn't seek re-election |
| Texas | Ted Cruz |
Ted Cruz |
No | Won |
| West Virginia | Joe Manchin |
Joe Manchin |
No | Won |
U.S. House
Battlegrounds are races that Ballotpedia expects to be particularly competitive, interesting, or meaningful to the future balance of power in Congress. Factors that we consider in naming a battleground election include the margins of victory from the previous few congressional elections in the district, how the district voted in the most recent presidential elections, whether a seat is open, if a particularly strong challenger has entered the race, and more.
The following map identifies those races that were considered battleground elections. Mouse over a district for more detailed information. You can also zoom in for a closer look.
Partisan breakdown
U.S. Senate
Heading into the election, the Republican Party held the majority in the U.S. Senate with 51 Senate seats. Democrats had 47 Senate seats. Two seats were held by independents who caused with the Democratic Party. In the 2016 elections, the Republican Party lost two seats but maintained its Senate majority.
| U.S. Senate Partisan Breakdown | |||
|---|---|---|---|
| Party | As of November 5, 2018 | After the 2018 Election | |
| Democratic Party | 47 | 45 | |
| Republican Party | 51 | 53 | |
| Independent | 2 | 2 | |
| Vacancies | 0 | 0 | |
| Total | 100 | 100 | |
U.S. House
Following the 2016 general election, the Democratic Party gained six seats. They picked up seven seats while only losing one in Nebraska. The Democratic Party fell short of the 30 seats required to retake the chamber. As a result, the Democratic Party needed to pick up 24 seats in 2018 to win the chamber.[3]
| U.S. House Partisan Breakdown | |||
|---|---|---|---|
| Party | As of November 5, 2018 | After the 2018 Election | |
| Democratic Party | 193 | 235 | |
| Republican Party | 235 | 200[4] | |
| Vacancies | 7 | 0 | |
| Total | 435 | 435 | |
Fundraising by candidate
The following charts show the top U.S. House and U.S. Senate fundraisers of the 2017-2018 election cycle based on FEC filings through October 23, 2018.
Fundraising by party
The Republican National Committee (RNC) raised over $192 million in 2018 compared to just under $110 million raised by the Democratic National Committee (DNC) during that same period. The RNC spent almost twice as much during the year as the DNC, with disbursements of over $207.5 million, while the DNC reported spending just under $108 million over the same period. As of the end of 2018, the RNC reported having $23.5 million of cash on hand and no debts owed. The DNC reported having $8.5 million as of the end of the year, with about $5.5 million of debt.
The Democratic Congressional Campaign Committee (DCCC) raised almost $191 million in 2018, which is $70 million more than the approximately $121 million raised by the National Republican Campaign Committee (NRCC). The DCCC raised about $85 million and spent over $141 million during the months of September, October, and November of 2018, while the NRCC raised about $52 million and spent over $96 million during the same period. As of the end of 2018, the DCCC reported having about $5.5 million in cash on hand and almost $19 million of debt, while the NRCC reported a cash balance of $16.5 million with $10.6 million of debt.
The National Republican Senatorial Committee (NRSC) raised over $109.5 million in 2018 while the Democratic Senatorial Campaign Committee (DSCC) raised over $94 million during the year. The NRSC spent about $117.5 million in 2018 with the DSCC spending approximately $107 million during the same period. Both parties' Senate campaign committees reported having more debt than cash on hand as of December 31, 2018. The NRSC had $7.5 million in cash and $17 million in debt as of that date, with the DSCC reporting just over $6 million in cash and over $21 million in debt at the end of 2018.
| 2018 annual fundraising for party national committees | ||||
|---|---|---|---|---|
| Organization | Total Receipts | Total Disbursements | Cash on hand | Debts Owed |
| National party committees (through/as of December 31, 2018) | ||||
| DNC | $109,820,208 | $107,882,227 | $8,550,791 | $5,625,873 |
| RNC | $192,326,316 | $207,643,381 | $23,501,561 | $0 |
| House campaign committees (through/as of December 31, 2018) | ||||
| DCCC | $190,962,396 | $224,247,395 | $5,615,496 | $18,943,553 |
| NRCC | $120,768,091 | $147,847,533 | $16,565,198 | $10,600,000 |
| Senate campaign committees (through/as of December 31, 2018) | ||||
| DSCC | $94,294,716 | $107,131,170 | $6,185,158 | $21,079,721 |
| NRSC | $109,652,458 | $117,423,685 | $7,497,936 | $17,000,000 |
- Note: This table summarizes data for 2018 as reported on each committee's Federal Election Commission (FEC) reports.
Outcome of recent presidential and gubernatorial elections
U.S. Senate
The following section compares data from recent presidential and gubernatorial elections with the party of the incumbent in each 2018 Senate race. These trends can be used as an early indicator of expected competitive Senate races in the 2018 elections. All of these statistics predict that the Democratic Party will be far more vulnerable than the Republican Party in the 2018 Senate elections.
There were 10 states with a Democratic incumbent that Donald Trump won in 2016:
Only one state with a Republican incumbent was won by Hillary Clinton in 2016: Nevada.
There were 13 states with a Democratic incumbent that have a Republican governor:
There are no states with a Republican incumbent and a Democratic governor.
There were four states that Barack Obama won in 2008 and 2012 that were won by Donald Trump in 2016—Florida, Michigan, Pennsylvania, and Wisconsin—but no states that were won by the Republican nominee in 2008 and 2012 (McCain and Romney) which were won by Hillary Clinton in 2016.
U.S. House
The following statistics were compiled using the Daily Kos' presidential results by congressional district data. They can be used to predict which districts are expected to be competitive in the 2018 elections.[5]
- There were 23 House seats held by a Republican incumbent that Hillary Clinton won in 2016: AZ-02, CA-10, CA-21, CA-25, CA-39, CA-45, CA-48, CA-49, CO-06, FL-26, FL-27, IL-06, KS-03, MN-03, NJ-07, NY-24, PA-06, PA-07, TX-07, TX-23, TX-32, VA-10, and WA-08
- There were 12 House seats held by a Democratic incumbent that Donald Trump won in 2016: AZ-01, IA-02, IL-17, MN-01, MN-07, MN-08, NH-01, NJ-05, NV-03, NY-18, PA-17, and WI-03
- There were 20 House seats that Barack Obama won in 2008 and 2012 which were won by Donald Trump in 2016: IA-01, IA-02, IA-03, IL-12, IL-17, ME-02, MN-01, MN-02, MN-08, NH-01, NJ-02, NJ-03, NV-03, NY-01, NY-02, NY-18, NY-19, NY-21, PA-17, and WI-03
- There were eight House seats that supported the Republican nominee in 2008 and 2012 (McCain and Romney) which were won by Hillary Clinton in 2016: AZ-02, CA-39, CA-45, CA-48, KS-03, NJ-07, TX-07, and TX-32
Candidate breakdown
As of February 19, 2026, the plurality of candidates who have filed or otherwise declared congressional runs are Democrats. A full breakdown of candidates by party can be seen below.
Cook Partisan Voter Index
The chart above details the 2018 Cook Partisan Voter Index for each U.S. House district. The index, developed by Charles Cook of the The Cook Political Report, compares each congressional district's score to that of the nation as a whole. According to Politico, the PVI is designed to "provide a quick overall assessment of generic partisan strength in a congressional district."[6][7][8]
Media coverage
The media highlighted various events that potentially impacted the outcome of the 2018 mid-term elections. This included major policy developments, the outcome of certain interim or special elections, and noteworthy national and international events. Such stories assessed the impact of these major events on the 2018 elections for the U.S. House or U.S. Senate, and sometimes, both.
Democratic primaries
- Katrina vanden Heuvel discussed the state of the progressive insurgency in the Democratic Party in an Atlantic article (August 16, 2018):
- "How do you cover an insurgency like the one now roiling the Democratic Party? The mainstream media’s treatment would give readers a severe case of whiplash. The 2018 primaries had barely started when The New York Times announced the virtual demise of the movement sparked by Bernie Sanders. Then, when newcomer Alexandria Ocasio-Cortez eviscerated Joe Crowley, the fourth-ranking Democrat in the House, in a New York primary, the Times ran a story headlined There Is a Revolution on the Left, warning that 'a new generation of confrontational progressives has put Democrats at the precipice of a sweeping transition.'
- "To date, the reform movement has made its greatest gains in the war of ideas. This shouldn’t be surprising. The reforms that the activists are championing are bold, striking, and address real needs: Medicare for all, tuition-free public college, a $15 minimum wage, universal pre-K, a federal jobs guarantee, a commitment to rebuild America, a challenge to big-money politics, police and prison reforms, and a fierce commitment to liberty and justice for all."
- "Moreover, the media too often assume that if the movement candidate has lost, a 'moderate' has won. ... The media need to focus less on the horse races and more on what’s being built and what’s being discarded. The insurgency is neither on its deathbed nor about to sweep out the old. Indeed, Democrats are still in the early stages of a huge debate on the party’s direction. Insurgent candidates are only starting to build the capacity to run serious challengers."[9]
Republican primaries
- Jonathan Bernstein discussed the significance of Trump's endorsement in Republican primaries in a Bloomberg article (August 22, 2018):
- "I’ve been impressed with Trump’s recent successes in primary endorsements. After the fiasco in the Alabama Senate special election, he’s been picking likely winners who then won, making Trump look good — and he’s restrained himself and stayed out of some contests in which the winner was difficult to determine in advance or where the Trumpiest candidate seemed unlikely to win. That streak ends in Wyoming."
- "The first tangible consequence for Trump is that he’ll most likely have a Wyoming governor who resents the president’s attempt to defeat him."
- "But the real danger here is that Republican politicians begin to believe that Trump isn’t a threat to them after all. My guess — and it’s only speculation — is that this has been true all along. While a presidential endorsement might move quite a few votes in low-interest primary elections because voters are looking for any kind of cue about who the acceptable candidate might be, it’s a lot harder for endorsements to move votes against an incumbent. Not impossible, but difficult."[10]
Special elections to the 115th U.S. Congress
In the 17 special elections called to fill vacancies in the 115th Congress in 2017 and 2018, nine Republicans and eight Democrats won. Four elections resulted in a partisan flip:
- Doug Jones (D), U.S. Senate in Alabama;
- Conor Lamb (D), Pennsylvania's 18th Congressional District;
- Mary Gay Scanlon (D), Pennsylvania's 7th Congressional District; and
- Susan Wild (D), Pennsylvania's 15th Congressional District.
Comparison of retirements
The following table includes figures on Democratic and Republican members of Congress who either left office during their term or announced that they would not seek re-election for each election year since 2012.
| Outgoing members of Congress, 2012-2018 | |||||||
|---|---|---|---|---|---|---|---|
| Year | Chamber | Democrats not seeking re-election | Republicans not seeking re-election | Total not seeking re-election | Democrats leaving office early | Republicans leaving office early | Total leaving office early |
| 2018 | |||||||
| U.S. Senate | 0 | 3 | 3 | 1 | 2 | 3 | |
| U.S. House | 18 | 34 | 52 | 3 | 14 | 17 | |
| Total | 18 | 37 | 55 | 4 | 16 | 20 | |
| 2016 | |||||||
| U.S. Senate | 3 | 2 | 5 | 0 | 0 | 0 | |
| U.S. House | 16 | 24 | 40 | 2 | 5 | 7 | |
| Total | 19 | 26 | 45 | 2 | 5 | 7 | |
| 2014 | |||||||
| U.S. Senate | 5 | 2 | 7 | 3 | 2 | 5 | |
| U.S. House | 16 | 25 | 41 | 3 | 6 | 9 | |
| Total | 21 | 27 | 48 | 6 | 8 | 14 | |
| 2012 | |||||||
| U.S. Senate | 6 | 3 | 10[14] | 0 | 0 | 0 | |
| U.S. House | 23 | 20 | 43 | 4 | 1 | 5 | |
| Total | 29 | 23 | 53 | 4 | 1 | 5 | |
Ballotpedia's Annual Congressional Competitiveness Report
Ballotpedia’s 2018 study of competitiveness in congressional elections found that nearly 13 percent of incumbent U.S. representatives and senators would not be on the 2018 general election ballot.
Wave election analysis
- See also: Wave elections (1918-2016)
The term wave election is frequently used to describe an election cycle in which one party makes significant electoral gains. How many seats would Republicans have had to lose for the 2018 midterm election to be considered a wave election?
Ballotpedia examined the results of the 50 election cycles that occurred between 1918 and 2016—spanning from President Woodrow Wilson's (D) second midterm in 1918 to Donald Trump's (R) first presidential election in 2016. We define wave elections as the 20 percent of elections in that period resulting in the greatest seat swings against the president's party.
Applying this definition to U.S. Senate elections, we found that Republicans needed to lose seven seats for 2018 to qualify as a wave election.
The chart below shows the number of seats the president's party lost in the 10 U.S. Senate waves from 1918 to 2016. Click here to read the full report.
| U.S. Senate wave elections | ||||||
|---|---|---|---|---|---|---|
| Year | President | Party | Election type | Senate seats change | Senate majority[15] | |
| 1932 | Hoover | R | Presidential | -13 | D (flipped) | |
| 1958 | Eisenhower | R | Second midterm | -12 | D | |
| 1946 | Truman | D | First midterm | -10 | R (flipped) | |
| 1980 | Carter | D | Presidential | -9 | R (flipped) | |
| 2014 | Obama | D | Second midterm | -9 | R (flipped) | |
| 1942 | Roosevelt | D | Third midterm | -8 | D | |
| 2008 | George W. Bush | D | Presidential | -8 | D | |
| 1926 | Coolidge | R | First midterm[16] | -7 | R | |
| 1930 | Hoover | R | First midterm | -7 | R | |
| 1986 | Reagan | R | Second midterm | -7 | D (flipped) | |
Analysis of federal elections, 2018
All 435 U.S. House seats and 33 U.S. Senate seats were up for regular elections in the 2018 midterms. Heading into the election, the Republican Party held a majority in both chambers.
Election issues
Throughout the course of the 115th Congress, we curated statements and reactions by members of Congress on a variety of different policy areas and topics. Click on a tile below to read about what members of the 115th Congress said about the following issues.
See also
- United States Senate elections, 2018
- United States House of Representatives elections, 2018
- United States Congress elections, 2016
- United States House Democratic Party primaries, 2018
- United States House Republican Party primaries, 2018
- Special elections to the 115th United States Congress (2017-2018)
Footnotes
- ↑ The American Presidency Project, "Seats in Congress Gained/Lost by the President's Party in Mid-Term Elections," accessed February 6, 2017
- ↑ Slate, "Are You Dreaming of Democrats Taking the Senate in 2018? Time to Wake Up." November 14, 2016
- ↑ The New York Times, "House Election Results: G.O.P. Keeps Control," accessed November 15, 2016
- ↑ One undecided 2018 race was decided in September 2019 when Dan Bishop (R) won the special election. The state board of elections called a new election following allegations of absentee ballot fraud in the 2018 race. Unofficial returns from the 2018 election showed Mark Harris (R) leading McCready, who was also the Democratic candidate in 2018, by 905 votes. Harris said he did not run again in 2019 due to health issues. Click here for more information on the aftermath of the 2018 election.
- ↑ Daily Kos, "Daily Kos Elections' presidential results by congressional district for the 2016 and 2012 elections," accessed February 8, 2017
- ↑ Politico, "Charlie Cook's PVI," April 10, 2009
- ↑ RedState, "New Cook PVIs Show Big Opportunities for Conservatives in the House," October 11, 2012
- ↑ Swing State Project, "Just what is the Partisan Voter Index (PVI)?" November 16, 2008
- ↑ The Nation, "The Democratic Insurgency Is Winning the War of Ideas," August 26, 2018
- ↑ Bloomberg, "Trump Endorsements No Longer Look Like a Golden Touch," August 22, 2018
- ↑ Daily Kos, "2008, 2012, & 2016 Presidential Election Results by District," accessed July 11, 2018
- ↑ 12.0 12.1 Both general election candidates were Democrats.
- ↑ Lamb won by a margin of 0.4 percentage points.
- ↑ Figure includes Sen. Joe Lieberman (I-Conn.).
- ↑ Denotes the party that had more seats in the U.S. House following the election.
- ↑ Calvin Coolidge's (R) first term began in August 1923 after the death of President Warren Harding (R), who was first elected in 1920. Before he had his first midterm in 1926, Coolidge was re-elected as president in 1924.
