Republicans build the wall against a blue wave

That’s why the midterm elections have become about the maps. A wave election usually requires two things: a sharp national turn against the party holding the White House and that party’s majority being disproportionately exposed in competitive districts or states.

The national environment has certainly deteriorated for Republicans since they won the trifecta — control of the White House, Senate, and House — in the 2024 elections. Democrats are favored in the generic congressional ballot by 5.9 points, according to the RealClearPolitics polling average. President Donald Trump’s job approval rating is down to 40.5%, and it’s even lower on specific issues such as the economy, inflation, and Iran. 

But how exposed are Republicans? One advantage they still have relative to past majorities that were swept away in wave elections is the number of safe seats.

When Democrats won the House during Trump’s first midterm election in 2018, widely held to be the last true wave election, Republicans represented more than two dozen districts Hillary Clinton had carried in the 2016 presidential election. Republicans managed to hold on to just three of them in 2018, accounting for half of the Democrats’ gains in that year’s election.

This time around, Republicans will only be defending three seats in districts won by former Vice President Kamala Harris.

“A bigger share of the current House majority is politically insulated. Fully 61% of Republican seats (134 of 220) are from districts Trump carried by at least 20 points,” elections analyst Steve Kornacki observed of last year’s numbers, before the redistricting wars began in earnest. “In 2018, fewer than half of the GOP’s seats were in this category. And more than 80% of GOP seats now are from districts Trump won by at least 12.5 points, compared to 66% in ’18.”

Democrats suffered even worse losses than the Trump-era GOP in the 1994 midterm elections under then-President Bill Clinton and in 2010 under then-President Barack Obama. At the time, Democrats still held a high number of seats in conservative districts. The southern party realignment was not yet complete in the early 1990s, and the Democrats’ congressional majorities in Obama’s first term were unsustainably large.

Once Democrats lost those seats in that pair of Republican wave elections, most of them remained safely GOP afterward. Something similar happened to GOP-held seats lost in the Democratic wave years of 2006 and 2018. 

It’s worth noting that this year’s House GOP majority is historically small, so Democrats won’t need to flip many seats to capture the lower chamber of Congress. In 2022, the red wave never fully materialized, but Republicans still won enough House seats to take control.

Republicans also still hold nearly 20 seats in districts Trump won by less than 7.5 points. They lost 15 out of 23 such districts in 2018.

Republicans are hoping this year’s redistricting fights and the Supreme Court’s Louisiana v. Callais decision will bolster the safety of their narrow majority while also creating new pickup opportunities. 

Both parties are looking to game the congressional maps for their partisan advantage. A combination of gerrymandering, voters sorting into states and congressional districts by partisan allegiances, and multiple wave elections benefiting both parties over the last 32 years has steadily reduced the number of true swing seats.

Some political analysts question whether a real wave election is even possible anymore.

But it is also possible that the national environment could deteriorate enough for the GOP to grow the universe of competitive seats, putting the majority beyond the reach of Republican redistricting efforts.

Under that scenario, Democrats could imperil not just GOP control of the House but also the Senate. Democrats are already pushing to contest Senate seats in Republican states like Texas, Alaska, Iowa, and Ohio, in addition to the somewhat swingier North Carolina. 

The redistricting wars wouldn’t end with a Democratic win in November, since Republicans believe they will gain seats in the future from the 2030 census. But the midterm elections could alter the terrain on which those wars are fought.