Charts of the week: Data from the Primaries Project

A woman leaves a voting station in a polling place at the Canterbury Town Hall polling station in Canterbury, New Hampshire February 9, 2016. REUTERS/Shannon Stapleton - D1BESMAVHBAB

In a new report from the Primaries Project, the authors write that “more and more people have realized that the key to understanding factions in American political parties is to understand congressional primaries.” Below are three charts taken from the many included in the new six-part report.

More challengers in Democratic House primaries in 2018

The percentage of Republican incumbents in the House of Representatives who have faced primary challenges has remained steady since 2010, whereas in 2018, 45 percent of Democratic incumbents faced challengers in the primaries. This is up from just under 28 percent two cycles ago. “This recent uptick is especially significant,” according to the report, “given that the Democratic Caucus in the House is quite small by modern historical standards.” However, only four House incumbents—two Republicans and two Democrats—lost their primary races this year.

Surge of Women Running in Congressional Primaries

Elaine Kamarck and Alexander Podkul write that the “[2018 primaries] cycle has made history for the large surge of women running in congressional primaries,” with the increase in Democratic women candidates particularly noteworthy. Kamarck and Podkul also observe that 39.9 percent of female non-incumbent candidates for the House won their primaries, compared to 24 percent of male non-incumbent candidates who won.


Kamarck and Podkul’s research shows that “it’s clear that the women candidates are focused on domestic issues, while the men are focused on international and business issues.” Thus, they continued, “if more women are elected this November, it could mean some changes in the congressional agenda.”

You can access all of the analysis and data by visiting the full report at “Political polarization and congressional candidates in the 2018 primaries.”