The 2018 congressional primary season has officially begun. Between now and the end of September, a few thousand candidates will compete to represent their party in November’s general election—and their success or failure will reveal how the country feels about President Trump as well as a host of other issues. These primaries will also tell us a great deal about the divisions within each political party, about which faction is dominant within each party, and about what we can expect from the Congress that will convene in 2019.
Here at the Brookings Primaries Project we will be examining and presenting the hard facts as the season unfolds. Let’s start with the lay of the land. At this point, as the following chart indicates, Republican incumbents stand to face more competition than their Democratic counterparts from two key sources. First, many more Republican incumbents are being primaried (i.e., challenged) by well-funded opponents from their own party. Second, in a telling measure, there are many more competitive Democratic primaries in Republican-held districts than competitive Republican primaries in Democrat-held districts. Competitive elections can both stem from and generate the entry of higher-quality candidates. They also attract media attention. This means that more Republican incumbents will have to deal with well-funded primary challenges and well-funded, battle-tested general election foes who can make news—prospects incumbents tend to dread. In addition, there are over twice as many Republican retirements as Democratic retirements in the House—usually an indication that the exiting members think it’s going to be a bad year for their party.
What the 2014 and 2016 primaries revealed
The status of the horse race isn’t the only revealing element of congressional primaries, however. Studying the candidates who are running in these primaries also tells us a great deal about the divisions within and between the political parties. As we prepare to study this year’s crop of candidates, it pays to look back at what we discovered in 2014 and 2016. In those years:
- House incumbents were consistently re-nominated (only three sitting members lost a primary in 2014 and only five lost in 2016).
- Progressive Democratic candidates made up nearly 30 percent of Democratic primary candidates in 2016.
- Conservative Republican candidates made up 50 percent of Republican primary candidates in 2016.
- The top issues mentioned by Republican candidates in 2016 were taxes, Obamacare, immigration, debt, and the Second Amendment while the top issues for Democratic candidates were Obamacare, Social Security, education, the minimum wage, and climate change.
- Primary margins of victory for incumbents have been consistent across the past two cycles with median margins near 50 percent for Republicans and near 65 percent for Democrats (Chart 11, 2016 report).
- In 2016, a presidential primary year, we wrote: “The drama in the presidential primaries, however, has not been mirrored in the congressional primaries. While we see more divisiveness at the congressional level among Republicans than among Democrats, the levels are small” (p. 18).
In addition to studying the congressional candidates, in 2016 we were able to study voters in congressional primaries as well. In that paper we asked, “Are primary voters different?” Some of our findings include:
- Republican voters were more likely to say that they chose to support their preferred House candidate because that the candidate “shares my values” or “can bring about needed change” while Democratic voters were more likely to support a candidate who “has the right experience” or “cares about people like me”
- On demographics, we found primary voters to be older and more educated than the general public.
In our two previous cycles, lessons from the congressional primaries were nearly perfectly predictive of what happened in the Congress. Republican majorities were focused on two issues that were at the top of the agenda for most congressional primary candidates: passing a tax cut bill, on which they succeeded, and repealing Obamacare, on which they failed. In addition, the Republican Party continued to be in the control of very conservative Republicans, while the Democratic caucus had a decidedly more moderate cast to it. Both of which could have been anticipated from the factional divisions apparent in the congressional primaries.
Examining the 2018 primaries and midterms
So what will we be looking for this year? On the Republican side, we’ll be looking at the degree to which “Trumpism”—that is, sharing the president’s issue positions and attitudes toward government—has trickled down to the congressional primary level. We’ll be identifying and counting the number of “mini-Trumps” running in this year’s primaries and we’ll be seeing how they do, especially in races against more mainstream Republicans. On the Democratic side, we’ll be looking for the progressive resurgence that has often been trumpeted as an outcome of Bernie Sanders’ run for president in 2016. We’ll see whether or not there are more self-identified progressives running, and whether they are explicitly identifying with Sanders and the organizations his candidacy has produced.
Given that America’s political parties are and have always been big tents, the study of primaries gives us a more nuanced and more useful way to look at American politics. We are pleased to be starting this project again and will report our findings regarding primary candidates and voters over the coming months.
 not including Ralph Hall (R-TX-4) who was defeated in a nomination runoff or Vance McAllister (R-LA-5) who was defeated in a nonpartisan blanket primary.