Inning two: Will 2018 be a “wave” election?

Three months ago, we asked in this space whether the extraordinary number of Democrats running against Republic incumbents in U.S. House elections were an early sign that 2018 might become a “wave” election.


A wave election is one in which a reasonably large number of seats switch parties in one direction but not the other. In recent years, the 2010 midterm election certainly qualified. Fifty-two formerly Democratic seats became Republican, two moved in the opposite direction, and the Congress changed from having 256 Democrats in 2009 (38 more than a 218-seat majority) to 242 Republicans in 2011.

The midterm election of 2006 was a smaller-scale wave election. The Democrats picked up 22 Republican seats, Republicans gained none, and Congress shifted from having 232 Republicans to 233 Democrats. In most other recent elections, seats changed in both directions and the net gain for either party was modest. (See Vital Statistics on Congress for the details.)

Going into 2018, the Republicans hold 241 seats in the House (including Republican vacancies) while the Democrats hold 194. The Democrats need a net gain of 24 to win a majority. In other words, they “only” would need a year that looked more like 2006 than 2010. But to do this, they would have to “sweep the board” by winning most of the seats that nonpartisan pundits see as being “tossup” seats or “leaning” Republican, while losing few or none of their own.

Two preconditions are necessary for this to happen. First, there has to be some issue or sentiment that shifts the country a few percentage points across the board. Second, there have to be attractive candidates running in enough districts to take advantage of the national forces.

Looking at the number of early challengers running for the House is one way to assess the second of these conditions. The sheer number of challengers is an indication of the depth of enthusiasm among potential candidates. For challengers who also have political careers, the willingness to run shows that they believe this year presents their best opportunity to win. When this enthusiasm is mostly among candidates for one party, this suggests that one party’s professionals see opportunities, while the opposition sees risks.

What can we say about 2017? Three months ago, the Campaign Finance Institute’s (CFI) analysis of mid-year reports filed with the Federal Election Commission (FEC) showed that more Democratic challengers had raised at least $5,000 than the comparable challengers in either party in recent years. In fact, the 2017 list was more than two-and-a-half times the previous high of 78 in 2009—the year before the wave election of 2010.  So the Democrats could take heart from those numbers. However, we also cautioned that the mid-year reports covered only the first inning of a very long game.

Three months later, we are now in the second inning. It is time to look at the latest FEC reports, filed on October 15 and covering the period through September 30. CFI’s analysis looked once again at the raw number of challengers. But to dig more deeply, it also looked at another measure that is more meaningful for the overall party balance.

Raw number of challengers

Record numbers of Democrats continue to emerge who are willing to defy the normal odds by mounting early challenges to sitting House incumbents. As of June 30, we counted 209 Democratic challengers who had raised $5,000 or more. Three months later, the 209 had grown to 391 Democratic challengers with at least $5,000. Of these 391, 210 raised at least $50,000 and 145 raised at least $100,000. The following table shows the comparison across years with the columns showing the number of challengers who have raised at least the amount indicated. (A full set of data, including for each of the candidates, is available on the Campaign Finance Institute’s website.)

As this shows, there were many more Democratic challengers at the end of September 2017 (at each financial level) than for any other party cohort since 2003. The Republican class of 2009 was in second place, with all others well behind. At each level, the GOP class of 2009 had fewer than half as many challengers as the Democrats of 2017.

Number of incumbents facing challengers from the opposite party

However, the raw number of challengers does not tell us all that we need to know. It is true that record numbers of Democrats have reacted to President Trump by deciding to run for Congress. But what if they are all jumping in against only a few potentially vulnerable incumbents? For example, eight Democratic challengers have filed FEC reports in the races against the incumbent, Jeff Denham, in California’s 10th district. Seven are running against Dana Rohrabacher in California-48, seven against Peter Roskam in Illinois-6, and seven against John Faso in New York-19. The most these 29 challengers can do in the general election is defeat four incumbents.

What we really want to know, therefore, is not how many challengers are running, but how many incumbents are facing challengers. The following bar chart graphically shows the number of incumbents running against challengers who have raised at least $50,000.

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For more detail, Table 2 shows the number of incumbents with opposite-party challengers in different cycles, and breaks down these incumbents by the amount raised by their best-funded challenger.  The number of districts in each row are cumulative, with each cell (except ones in the “zero” column) being a subset of the one to its left. For example: in the first line of the table on the left, the 73 Democratic challengers who raised at least $100,000 in 2017 are also part of the 98 with at least $50,000, and so forth.

This table tells us that many more Republican incumbents are facing Democratic challengers at this time of the year (at each funding level) than any other set of incumbents since 2003. Because multiple candidates are in fact running in some districts, the advantage is not quite as large as it was for the raw number of challengers. There were more than twice as many Democratic challengers in 2017 as Republicans in 2009. When we flip the question around, there are just short of one-and-a-half times as many Republican incumbents facing Democratic challengers in 2017 (at the various funding levels) as the other way around in 2009. While not as large an advantage as the raw number of challengers suggests, this is still considerable. The 2009 GOP cohort was larger than any other before this year. It was large enough to feed a major partisan shift in 2010—and larger than the Democrats need to become a majority in 2018.

What should we make of all this?

Given the field of challengers, should we expect a Democratic wave in 2018 that could rival the 2010 wave for Republicans? These numbers tell us that Democrats are poised to take advantage of a wave if one develops. And based on past experience, a wave election would likely sweep out some incumbents who are not yet even challenged. But the challengers cannot make a wave election by themselves. That will depend upon the President’s performance, Congress’s performance, and the mood of the public. In other words, it is still the second inning. There are many more yet to be played.