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How to Define a Wave

With President Trump's job approval ratings up, the economy humming and the congressional ballot tightening, it no longer looks as dire out there for GOP. Some, like Washington Post’s Michael Scherer, argue that “shifts in the national mood raise the possibility that an anticipated electoral wave could flatten into a ripple.”

In a tweet last week, National Journal’s Josh Kraushaar points to a recent poll in TX-07 that shows a generic ballot of R+1 and the incumbent GOPer, John Culberson, up two points on the Democratic nominee, as “good” but that “don’t suggest a huge D wave.”  The New York Times’ Nate Cohn tweeted recently:

So, what is a ‘wave’ election? And, how will we know if we are in one — or even in November, that we actually had one?

To be clear, anything other than flipping control of the House this fall will be a disaster for Democrats. Even if they win 20 seats — something that could technically be defined as a ‘wave,’ the election will be defined as a ‘win’ for the GOP.

Given that, can we call Democrats picking up 23 seats, the bare minimum needed to pick up the House, a wave?

In the most recent wave elections for the House — 1994, 2006 and 2010 — the party out of power picked up significantly more seats than they needed to win control. 



By this metric, a gain of 35 seats by the Democrats should be considered a wave.

There is also an assumption, as Cohn alludes to in his tweet, that the winning party is going to win competitive seats by huge margins. Which is why many see polling in places like TX-07 and PA-01 that show the incumbent in a dead heat — or slightly ahead — of the Democratic nominee as a sign of ripple, not a wave. If the political environment is this bad, shouldn’t these incumbents be losing? 

Democrats have a structural, not environmental, challenge when it comes to the House. In order to net 23+ seats, they've got to win in places where Republicans have typically prospered. That means that even if they win these seats, it will likely be by small margins. 

In fact, what has happened in past waves is that the closest races — those in Toss-Up — break disproportionately for the winning side. Think of it like sailboats racing toward a buoy. They are bunched up right until they get close to the mark and then a big gust of win pushes just one team’s boats ahead. 

In 2006, we had 38 Republican-held seats in Toss-Up. Democrats won 21 — or 55 percent of them. 

More important, Democrats won half of those seats (11) with under 52 percent and all but two, with under 55 percent of the vote. 

In 2010, Republicans won 65 percent of the Democratic seats in Toss-Up (32 of 49). Republicans won two-thirds of those races by 52 percent or less. 



This year, Republicans have 23 seats in toss-up and six in lean Democrat or worse. That means Democrats would need to hold all of their own seats in toss-up (2), win the six leaning their way, and win 17 — or 73 percent of the toss-up seats.

That 73 percent win goal is a much steeper one than Democrats faced in 2006 or Republicans had to hit in 2010. It means that the biggest challenge for Democrats is to make the 27 GOP-held seats that are sitting in Lean Republican, more competitive by this fall.

Ultimately, if those seats that now advantage Republicans start to look more competitive, we can feel more confident we are in the midst of a wave. If not, Republicans may be able to hold down their losses and hold onto their majority.