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Primary election competitiveness in state and federal government, 2020

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Last updated on August 5, 2025[1]
2020 State Legislative Competitiveness
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2020 State legislative competitiveness
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In 2020, Ballotpedia published state and federal primary election competitiveness data following each state's major-party candidate filing deadline. This includes data from congressional, state legislative, and state executive filings.

The statistics in this report include the percentage of contested partisan primary elections in 2020, the percentage of incumbents who sought re-election, and the percentage of incumbents with a primary challenger. Click here for primary election competitiveness data for the United States.

A contested primary is defined as one in which voters have a choice on the ballot. Most commonly, this means that there is more than one candidate from one party in the race. Exceptions to this include states with multi-member legislative districts and states using a top-two primary system, such as California and Washington.[2]

Overview

The following statistics are an aggregate of primary election competitiveness data across all states with completed filing deadlines. Corresponding data from 2014 and 2016 are provided for comparative purposes.

  • In 2020, an average of 2.3 candidates per seat filed for election compared to 2018 when 2.4 candidates per seat ran. In 2016, 2.2 candidates per seat ran, and in 2014, 2.1 candidates per seat ran on the ballot.
  • 15.0% of seats were open.[3] Comparing to previous cycles, 20.0% of seats were open in 2018, 17.4% in 2016, and 16.9% in 2014.
  • 20.5% of possible primary races were contested in 2020. Comparatively, 23.2% of primaries were contested in 2018, 19.1% in 2016, and 18.2% in 2014.
  • 22.7% of incumbents had contested primaries. In 2018, 24.9% of incumbents had a primary opponent. In 2016 and 2014, respectively, 22.8% and 21.7% of incumbents had contested primaries.

In general, congressional elections had more contested primaries, followed by statewide executive races. The further down-ballot a race is, the less likely it was to be contested.

The table below shows cumulative primary competitiveness and incumbency statistics by office. You may need to move the table horizontally using the scrollbar at the bottom of the table depending on your screen size.

2020 aggregate primary competitiveness data
Office Total seats Open seats Total candidates Democratic primaries contested Republican primaries contested Top-two primaries contested Total contested Incumbents contested in primaries Total incumbents contested in primaries
U.S. Senate 33 4 242 22 22 1 69.2% 15 53.6%
U.S. House 435 41 2,052 198 200 63 58.1% 198 50.3%
State executives 144 49 510 36 43 21 39.1% 35 36.5%
State legislature 5,875 876 12,353 836 882 109 17.0% 1,006 20.1%
Totals 6,487 970 15,157 1,092 1,147 194 20.5% 1,254 22.7%


The below tables contain the same aggregate information for the previous years.

2018

2018 aggregate primary competitiveness data
Office Total seats Open seats Total candidates Democratic primaries contested Republican primaries contested Top-two primaries contested Total contested Incumbents contested in primaries Total incumbents contested in primaries
U.S. Senate 33 3 249 14 29 2 70.3% 15 50.0%
U.S. House 435 60 2,015 241 170 55 58.5% 190 50.8%
State executives 264 100 1,029 96 106 21 45.5% 67 40.4%
State legislature[4] 6,065 1,194 13,297 1,005 1,011 107 19.3% 1,082 22.2%
Totals 6,797 1,357 16,590 1,356 1,316 185 23.2% 1,354 24.9%

2016

2016 aggregate primary competitiveness data
Office Total seats Open seats Total candidates Democratic primaries contested Republican primaries contested Top-two primaries contested Total contested Incumbents contested in primaries Total incumbents contested in primaries
U.S. Senate 36 5 266 20 22 3 65.2% 18 58.1%
U.S. House 435 45 1,588 133 170 55 44.8% 196 50.4%
State executives 91 42 300 28 29 9 38.8% 20 39.2%
State legislature[5] 5,916 1,032 11,918 752 940 108 16.6% 985 20.2%
Totals 6,478 1,124 14,072 933 1,161 175 19.1% 1,219 22.8%

2014

2014 aggregate primary competitiveness data
Office Total seats Open seats Total candidates Democratic primaries contested Republican primaries contested Top-two primaries contested Total contested Incumbents contested in primaries Total incumbents contested in primaries
U.S. Senate 31 6 191 15 23 1 63.9% 14 56.0%
U.S. House 435 43 1,471 119 161 53 41.7% 167 42.6%
State executives 211 68 728 71 79 8 38.3% 51 36.4%
State legislature[6] 6,051 1,019 12,046 646 958 94 15.5% 983 19.5%
Totals 6,728 1,136 14,436 851 1,221 156 18.2% 1,215 21.7%

Breakdown by office

U.S. Senate



U.S. House


State executive


State legislative


See also

Footnotes

  1. The numbers reflected here are subject to change by the time of the general election. Additionally, Ballotpedia is currently conducting a decade-wide audit of all state legislative elections in order to standardized data from previous years.
  2. In the case of top-two or nonpartisan primaries, all candidates are included in the total number of candidates regardless of their party affiliation.
  3. This analysis defines a seat as open if the incumbent did not file to run for re-election or filed to run for re-election but withdrew before the primary filing deadline.
  4. State legislative elections in Nebraska's nonpartisan Senate were not included in this analysis.
  5. State legislative elections in Nebraska's nonpartisan Senate were not included in this analysis.
  6. State legislative elections in Nebraska's nonpartisan Senate were not included in this analysis.