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With just under a month to go until Election Day, financial decisions made by both parties appear to suggest the question being asked is not if Democrats take control of the House, but how large the majority may be.

Currently, Republicans hold a narrow 218-214 seat advantage. In February 2025, the Cook Political Report’s initial ratings for the midterms found a small slice of 39 races listed as competitive, with 18 classified as “toss-ups.”

That topline number has shifted, with Cook currently listing 43 districts as competitive, including 22 toss-ups. But beyond that, under the hood, Democratic and Republican groups are marshalling hundreds of millions of dollars to influence an electoral landscape that is much larger.

An NPR analysis of both parties’ campaign targets, future ad reservations and outside spending by Trump-aligned super PACs finds more than 90 districts where resources are being committed in the closing weeks of the midterms.

Here’s a look at the types of races that will decide who controls the House in 2027.

Competitive races on paper

If the political environment remained unchanged from the 2024 presidential election, a small group of House races would be competitive no matter what, like the 10 districts that voted for one party’s presidential candidate and the other party’s House nominee. (Not counting those changed by redistricting in the last 18 months, but more on that below)

That includes the seats held by New York Republican Rep. Mike Lawler (NY-17), Pennsylvania Republican Rep. Brian Fitzpatrick (PA-01) and Washington state Democratic Rep. Marie Gluesenkamp Perez (WA-03).Another group of seats had very close margins in 2024, like Democratic Rep. Adam Gray’s victory by fewer than 200 votes in California’s 13th Congressional District and a 799 vote victory for Republican Rep. Mariannette Miller-Meeks in Iowa’s 1st Congressional District.

But this is not the same political environment as 2024. President Trump’s unpopularity with voters has reached record highs, with the share of voters who strongly disapprove of his job performance sitting higher than any point in either term in office.

Voters are unhappy with the ongoing war in Iran, rising gas prices, tariffs and immigration enforcement, and a wave of anti-incumbent sentiment has driven a record number of Congressional retirement announcements along with a number of sitting lawmakers losing their primary races this year.