The home stretch is finally upon us. We’re less than 60 days out from the midterms, and while there are a couple of primaries left on the calendar—New Hampshire on Tuesday and Rhode Island on Wednesday—neither is expected to alter the big picture. Both parties have found themselves on an emotional roller coaster this year: Democrats lost a pair of 10-term congressional incumbents at the hands of progressive insurgents, while Republicans saw an alt-right–friendly candidate claim one of its Senate nominations and watched nervously as a convicted coal baron made a high-profile attempt to snatch another.
And yet the overall state of play in the battle for control of Congress remains largely unchanged since one year ago. The short version: Democrats are looking good in their bid to retake the House. Meanwhile, the position they find themselves in the Senate, to use a technical political-science term, is meh.
A necessary epistemological caveat: Nothing is guaranteed. Historical precedents are important, but by definition they can only tell us what happened in the past. Likewise, polls are a snapshot of where things stand today, not how they’ll look tomorrow. We can use both to make educated guesses, but political forecasting is an imperfect science, regardless of whether you’re a number cruncher like FiveThirtyEight’s Nate Silver or a politics professor like the University of Virginia’s Larry Sabato.
That said: Nearly all of the available evidence suggests Democrats will pick up seats in the House, though not necessarily the 23 they need to retake the chamber.
For starters, there’s history. The party that doesn’t control the presidency has gained congressional seats in 35 out of the 38 midterms dating back to the end of the Civil War. And according to the Cook Political Report’s count, there have been seven midterms elections since 1966 where a president’s approval rating “hovered” below 50 percent—an, um, generous term for where Donald Trump’s sits at the moment—and in those, the opposing party has picked up at least two dozen House seats in all but one. The sole exception was in 2014 in the middle of Barack Obama’s second term. The GOP won “only” 13 seats that year, in no small part because Democrats didn’t have all that many to lose after getting shellacked in the 2010 midterms.
The polls suggest that general trend will continue. Democrats are up 7.8 points in RealClearPolitics’ unweighted average of the generic ballot and ahead 8.5 points in FiveThirtyEight’s weighted one, which prioritizes higher-rated pollsters. (Those margins were 9.3 and 8.1, respectively, on March 6, the day of the first midterm primary, and 8.6 points and 8.1 points this time last year.) But flipping House seats isn’t the same as flipping enough of them. And Democrats have their work cut out there. Thanks to gerrymandering, geography, and other factors, the GOP has a sizable built-in advantage in congressional races. Experts disagree on the true size of the cushion, but most think Democrats will need to win the national vote by somewhere between 4 and 11 percentage points to gain control of the House. As they have for most of the year, Democrats are currently splitting the difference.
But while Democrats’ edge in the generic ballot has waxed and waned, nonpartisan handicappers have moved one race after another in their direction. Cook, for example, currently believes 66 GOP seats are in play, 28 more than it did in January. Over that time, the number of Democratic seats in play fell from seven to five.
In Pennsylvania, where the state Supreme Court redrew the congressional map this year, Democrats have a chance to pick up six seats, including in the new 17th District, where the Democrats’ special-election hero Conor Lamb is up against Rep. Keith Rothfus. In North Carolina, where a federal court recently decided it’s too late to redraw an unconstitutionally gerrymandered map before November, Democrats nonetheless have a real shot at picking up three seats, including in the 9th, where U.S. Rep. Robert Pittenger lost his GOP primary to pastor Mark Harris, opening the door for Democrat Dan McCready. And in California, Republicans are defending seven seats in districts Trump lost two years ago—a list that doesn’t include the 50th, where GOP Rep. Duncan Hunter has been indicted for fraud and campaign finance crimes. (Anyone wanting to keep tabs on these and other exciting midterm races should subscribe to Slate’s Hot Seats newsletter.) With so many openings, Democrats have a variety of different paths to control of the House.
And what about the Senate, where Democrats have to pick up just two seats to take control? If House Democrats appear destined to gain seats, why isn’t that the case for their colleagues in the upper chamber? The first and foremost reason: a truly unforgiving midterm map.
Thanks to the quirks of the electoral calendar, in which roughly a third of the seats are up every two years, more than half of the 49 members of the Democratic caucus face re-election this fall—and 10 of those 26 incumbents are running in states Trump won two years ago. Meanwhile, Republicans are defending just nine of their 51 seats, only one of which is in a state Trump lost (Nevada).
Cook and other nonpartisan handicappers currently think Democrats have a real chance of flipping just four GOP-held seats: Arizona, Tennessee, and Nevada are toss-ups, while Texas is within Beto O’Rourke’s reach. If Democrats win two of those—a solid haul!—they’d still need each and every one of their own incumbents to survive. And if Democrats were to sweep all four—a Texas-size if—Republicans would still keep control of the chamber if they can knock off three red-state Democrats, five of which are running in toss-ups and another two of which are considered vulnerable. Democrats’ margin for error in the Senate, then, isn’t just smaller than it is in the House—it is nearly nonexistent.
One more thing
If you think Slate’s work matters, become a Slate Plus member. You’ll get exclusive members-only content and a suite of great benefits—and you’ll help secure Slate’s future.Join Slate Plus