U.S. House battleground primaries, 2018

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Elections were held for all 435 U.S. House seats in 2018. In the majority of these races, at least one major-party primary election was uncontested. However, every year there are a few congressional primaries that capture the attention of the nation. This page served to highlight those primary races that Ballotpedia expected to be competitive or interesting in some other way. Primary races were added to this page as they developed, although that usually didn't happen until after filing deadlines.

Criteria

See also: Battlegrounds

It is typically difficult to predict how competitive primaries will be until after filing deadlines take place. However, Ballotpedia put together a number of factors that were used to give insight into the most interesting 2018 primary elections. Factors that were used to determine the competitiveness of primaries included:

Whether or not the seat was open (retiring or resigning incumbent)
Notable endorsements of multiple candidates
Significant fundraising from multiple candidates
Number of candidates
Incumbent's years in office (if seeking re-election)
Whether or not the district's general election was expected to be a battleground

Battleground primaries

Democratic primaries

Republican primaries

Battleground general elections

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.

Cook Partisan Voter Index

See also: The Cook Political Report's Partisan Voter Index

The chart above details the 2017 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."^[1]^[2]^[3]

2016 stats

HIGHLIGHTS

In 2016, 44.53% of major-party primaries were contested, an increase from 39.5% in 2014.

Republican primaries were more competitive than Democratic primaries. Republicans saw a rate of competition of 46.17%, while only 36.89% of Democratic primaries were contested.

Five incumbents were defeated in 2016. This amounts to a very slim 1.3% of all incumbents who sought re-election.

Defeated incumbents

Five incumbent members of Congress lost their primary elections in 2016—a slightly higher number than the past decade's average. This slight increase can be explained by the court-ordered redistricting that took place in several states. Redistricting played a role in three of the five incumbent losses, one of which was an incumbent-versus-incumbent battle.

Redistricting also explains why so many incumbents were defeated in the primaries in 2012, the first election after maps were redrawn following the 2010 census. In 2012, eight incumbent members of Congress lost to another incumbent in the primary as a direct result of redistricting.

Comparison of retirements

See also: List of U.S. Congress incumbents who did not run for re-election in 2018

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^[4]	0	0	0
	U.S. House	23	20	43	4	1	5
	Total	29	23	53	4	1	5

Footnotes

[1] Politico, "Charlie Cook's PVI," April 10, 2009

[2] RedState, "New Cook PVIs Show Big Opportunities for Conservatives in the House," October 11, 2012

[3] Swing State Project, "Just what is the Partisan Voter Index (PVI)?" November 16, 2008

[4] Figure includes Sen. Joe Lieberman (I-Conn.).

[1]

[2]

[3]

[4]

U.S. House battleground primaries, 2018

Contents

Criteria

Battleground primaries

Democratic primaries

Republican primaries

Battleground general elections

Cook Partisan Voter Index

2016 stats

Defeated incumbents

Comparison of retirements

See also

Footnotes

Information about voting

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