A wave of anti-incumbent sentiment is rippling through both political parties ahead of the 2026 midterm elections, with Republicans and Democrats alike seeing veteran lawmakers fall in primary contests as strategists debate what it could mean for control of Congress.

Republicans hold a slim 218-212 advantage in the House, with one independent and four vacancies, while the GOP is also defending its Senate majority after Sens. Bill Cassidy of Louisiana and John Cornyn of Texas lost their primary bids.

According to The Hill, National Republican Senatorial Committee Chair Tim Scott has privately cautioned fellow Senate Republicans "about how bad polling is, currently, for Republicans and how bad the president is losing ground among all groups," citing a senior GOP aide.

Senate Republican Conference Chair Tom Cotton also reportedly shared polling showing independent voters shifting away from Republicans.

Veteran Republican pollster Whit Ayres said history shows a president's job approval often plays a major role in midterm outcomes.

"We know that the party in power tends to lose House seats in a midterm election, but the number of seats lost is highly correlated with the president's popularity. When presidential job approval is above 50%, the average loss of House seats for his party is 14. When it's below 50%, the average loss of House seats for his party is 32," he said.

Ayres added there is "a lot of variation around those numbers" because of redistricting and political polarization but noted "there are very few people at this point who are predicting that the Democrats will not gain seats in the House."

This year's primaries have already unseated eight House incumbents — five Democrats and three Republicans — underscoring voter dissatisfaction with political insiders.

Kyle Kondik, managing editor of Sabato's Crystal Ball at the University of Virginia's Center for Politics, said the anti-establishment mood spans both parties.

"This is going to be a big year for primary losses in the House," Kondik told The Hill. "There have already been eight incumbents who lost. ... There's generally a sour mood in the country and you've already seen over the course of the last 10 to 15 years the Republican establishment became less and less powerful and popular and has basically been replaced by a new establishment, which is Trump."

Kondik also said there is "a Democratic Tea Party movement going on" and added, "There's an anti-establishment feeling on both sides."

Republican pollster Jim McLaughlin argued the GOP could blunt any political headwinds by contrasting its agenda with the Democratic Party's increasingly progressive wing.

"The ones that lose on the Republican side aren't sufficiently pro-America First, Trumpy, and the ones who are losing on the Democratic side, which is a big problem for the Democrats, is they're not socialist enough," he told The Hill.

"It's not just in New York City, look at Colorado — they're nominating Marxist extremists in their primaries, and all Democrats are going to have to answer," McLaughlin added.

Ayres said populist energy is reshaping both parties but cautioned that winning a primary is only the first hurdle.

"The first is winning general elections, which is a whole different story with a completely different electorate," he told the outlet. "The second is, if they should win a general election, coming up with a credible positive agenda rather than just railing against what is."