Republicans Are Building an Advantage in Redistricting. How Much?

The redistricting wars heading into the November midterm elections had been in a stalemate, with each party’s tit-for-tat gerrymanders roughly canceling each other out.

It’s not a stalemate anymore. Over just the last two weeks, new court rulings and new congressional maps have put Republicans on track to add more than a dozen districts that voted for President Trump. It would be enough for Republicans to obtain a significant structural advantage in the House of Representatives, giving them a much better chance to at least stay competitive even if they lost the combined national vote by a wide margin in the midterms.

On procedural grounds, the Virginia Supreme Court on Friday struck down a Democratic-drawn congressional map that had been approved by voters. The map had been the centerpiece of the party’s effort to counter Mr. Trump’s mid-cycle redistricting campaign. The decision was entirely unrelated to the Supreme Court’s decision allowing states to dismantle majority-minority districts, which has triggered a rush of new Republican redistricting efforts across the South. For good measure, Florida Republicans redrew their state’s map, potentially adding up to four new Republican districts.

With Mr. Trump’s approval rating stuck below 40 percent and Democrats building a growing polling lead in the race for Congress, even a dozen new Trump districts might not be enough for Republicans to retain the House. But while Democrats remain favored, retaking the House is no longer a foregone conclusion. The new maps make it much easier to imagine how the midterms could be a seat-by-seat battle for House control — one which Democrats could well be favored to win, but which would not feel like the sweeping “wave” election it might have been otherwise.

It’s important to emphasize that this cycle’s redistricting fight has been surprising from the start, and the details remain in flux. Florida’s new congressional map, which was enacted on the grounds that the Supreme Court’s recent decision invalidates the state constitution’s prohibition on gerrymandering, faces serious legal challenges. Litigation is ongoing in other states, including Virginia. And so far, only Tennessee has enacted a new map in response to the Supreme Court’s decision on the Voting Rights Act. Louisiana, South Carolina and Alabama are expected to follow, but maybe one or two will not — or maybe additional states, red or blue, will join the fight.

But if everything stays as is — and with Alabama, South Carolina and Louisiana enacting new maps — Republicans will obtain a significant structural advantage. To win the House, Democrats could need to win the House combined national popular vote by around four percentage points, according to our estimates.

A four-point structural advantage wouldn’t be enough to make the Republicans favorites to win the House, but it gives them a real shot at it. In polling averages, Democrats lead by six points on the so-called generic congressional ballot, which asks voters which party they’ll support for Congress. But if Republicans make gains between now and November or pull off enough victories in key races, they could have a chance to retain control of the House even while losing the national vote by a significant margin.

A different way to consider the Republican advantage is to look at the kinds of seats they would need to win. Here, the most popular measure is the median congressional district — the district that would serve as a tipping point for House control. By this measure — after the Southern states redraw their maps — the median district will have voted for Mr. Trump by 5.5 points in 2024, or about four points more Republican than his 1.5-point margin in the 2024 national popular vote.

By each measure, Democrats need to win districts that voted Republican by a comfortable margin, though it may not be quite as challenging as it sounds. For one, there are nearly 50 districts where Mr. Trump won by five to 15 points. Democrats do not need many to break their way, and historically breakthroughs like these tend to happen when the national environment swings decisively in one direction.

For another, many districts that backed Mr. Trump by a wide margin have a recent record of voting for Democrats, including many with large Hispanic populations and many of the newly Republican districts created in this cycle’s redistricting wars. As a result, many Republican gains from redistricting might fail to materialize in this national environment: Democrats might hold districts like Florida’s 25th or 14th; Texas’ 28th, 34th or 35th; or North Carolina’s First.

And Democrats might flip some of the seats they targeted in their ill-fated Virginia gerrymander the old-fashioned way, like Virginia’s Second or even Virginia’s First.

On the other hand, these seats are so Republican that it’s easy to see how Democrats could fail to break through. If the Supreme Court’s Voting Rights Act decision and Mr. Trump’s mid-cycle redistricting campaign allowed Republicans to win the House while badly losing the national vote, it would be yet another blow to the credibility of American institutions during a time of bitter division.