So far this election cycle, most analysts have assumed that Democrats will win the House next November. No, it’s not a guarantee. But the party out of the White House usually does well in midterms, and Democrats need a mere three seats to retake the chamber.

Over the last few weeks, this reasonable assumption has started to get more complicated. It turns out that Democrats might need to flip more than three seats, as President Trump is pushing red states to undertake a rare mid-decade redistricting effort to shore up the slender Republican House majority.

On Wednesday, Republicans in Texas unveiled the first of these efforts: a new map that could flip as many as five seats from blue to red.

It’s still too early to say what might happen beyond Texas. Maybe other Republican states will join; maybe Democrats will retaliate. Obviously, a wider redistricting war could have far greater implications, to say nothing of whether it is healthy for the country. But on its own, while the Texas map makes the Democrats’ path to the House harder, it doesn’t necessarily make it hard. They would still be favored to win the House if the election were held today on the new map, even though they don’t hold a very large lead in the polls.

The current national congressional map remains more or less balanced by the usual measures of partisan fairness.

The House map was fundamentally balanced

If you’ve been following American politics for a decade or more, you might be under the impression that Republicans enjoy a significant structural advantage in the fight for control of Congress, thanks in no small part to partisan gerrymandering.

While this was a reasonable supposition a decade ago, it’s really not so true anymore. Republicans no longer have a meaningful structural edge in the chamber at all. By some measures, Democrats actually had a slight edge recently: They nearly won the House in 2022 even though they lost the popular vote.

What happened? For one, the great Republican gerrymander of the early 2010s was taken apart. Today, former Republican gerrymanders in states like Michigan, Florida, Pennsylvania, Ohio and Virginia have been replaced by much fairer maps, thanks to a mix of favorable court rulings, referendums and legal changes. Yes, there are still many Republican gerrymanders — like in North Carolina and Texas (both before and after the redraw) — but Democrats have countered with gerrymanders of their own, like in Illinois or Nevada, partly canceling it out.

For another, recent electoral trends have positioned Democrats to win House elections more easily. The Republican advantage in the early 2010s was partly a reflection of the geographic distribution of the Obama coalition, which showed its greatest strength in urban areas where Democrats had already been winning House elections. Since then, Democrats have made big gains in highly educated suburbs, flipping many previously Republican-leaning districts. At the same time, the collapse of the Obama coalition cost Democrats many popular votes in urban and rural areas but didn’t cost them many House seats. Put it together, and today’s congressional map is arguably the most balanced map since the enactment of the Voting Rights Act in 1965.

Perhaps the easiest way to tell: Democrats barely lost the House popular vote in the last two elections, and they barely lost the chamber. By some measures — including the so-called efficiency gap promoted by redistricting reformers — the current House district map actually leans slightly to the left. By others — including my preferred measures — the map leans slightly to the right.

Either way, the fundamentally balanced House map is the backdrop to the new Texas map. While a few more Republican seats will certainly help the G.O.P., it will take more to give Republicans a major structural advantage in the fight for the House.

The new Texas map

How much will the Texas plan help Republicans? It’s worth breaking the changes into two groups.

First, the new map turns three Democratic-held districts that voted for Kamala Harris in metropolitan Texas into Trump districts. Realistically, Republicans will flip all three seats next November.

Second, the new map makes two heavily Hispanic Democratic-held districts that already voted for Mr. Trump even more Republican. However, it doesn’t necessarily make them so much more Republican that it rules out a Democratic victory.

The second group of districts makes it harder to say this map will flip five seats. For one, there was a real chance that Republicans could have flipped these seats without redrawing the map, as they were already competitive last November. For another, Democrats might still hold these districts. They have Democratic incumbents, and they’re full of traditionally Democratic Hispanic voters. Even as redrawn, these districts voted for Joe Biden in 2020. Add in a favorable midterm environment, subtract the relatively Trump-friendly general election turnout, and add the variable of a less predictable Hispanic vote, and suddenly there are a lot of ways Democrats could hang tough in these seats next year.

What does that suggest for Democrats’ chances to win the chamber? Three to five seats is enough to be meaningful, but not enough to fundamentally change the national picture. Here are two ways to think about it.

In terms of Trump districts: To take the House in 2024, Democrats needed to win at least one district where Mr. Trump won by three or more points. If the Texas map were approved, Democrats would now need to win at least one district that Mr. Trump won by four or more points — as in a seat that’s about 2.5 points better for Mr. Trump than his 1.5-point victory in the national vote.

That 2.5-point gap is a modest structural edge for the Republicans, but it pales in comparison with the six-point structural edge the G.O.P. enjoyed in 2016 or the four-point edge they had going into the 2018 midterms. It’s comparable to 2020, when the Democrats held the House in a close election.

In terms of races: Democrats were only three seats away from winning the House in 2024, and the three closest Republican-won races were all decided by a point or less. Since the Republicans won the national House vote by two points, by this measure the House map actually tilted toward Democrats.

Let’s say Republicans flip all five seats in the new Texas map, and so Democrats need to win eight other seats. In 2024, the eight closest races were decided by three points or less. Here again, the Texas map makes things more challenging for Democrats, but it’s still not unusually different from the national vote.

By each measure, the Texas map makes the task a bit tougher for Democrats, but not by so much that it would prevent them from capitalizing on what ought to be a favorable midterm year. That said, three to five seats could easily be the difference in a very close election.

What about a national redistricting war?

While the new Texas map doesn’t give Republicans an enormous advantage, Republicans in other states might need to redraw only a few more districts before the burden on Democrats started to seem more significant.

If Republicans gerrymandered another five districts in their favor, for instance, Democrats would need to win seats that voted for Mr. Trump by more than five points; and they would need to sweep the usual tossup districts. Democrats could pull this off in a so-called wave election, like in 2018, but today the party is ahead by only three points or so in polls of the generic congressional ballot. The party out of power often gains as the midterms near, but for now it would be dicey.

Could Republicans add many more seats? It wouldn’t be as easy as in Texas, but it’s possible. There are a handful of states besides Texas, like Missouri and Indiana, where a Republican state legislature could eliminate Democratic-held seats without running afoul of the Voting Rights Act or state constitutional limitations. Beyond that, there are other states where such an effort is plausible but would face at least some legal obstacles, like Ohio and Florida. On the other hand, Democrats could retaliate in blue states, though they’re generally more hampered by state law.

All of this is speculative at this early stage. While the House picture remains fundamentally similar for now, it’s possible to imagine how that might change in the future.