Republicans are pouring money into more than three dozen US House races previously considered “safe” after internal polling showed they could be vulnerable in the November 3 election, according to three Republican operatives familiar with the party’s thinking.

The shift is already starting to show in advertising reservations and campaign finance filings. Since September 1, major Republican groups and megadonors have begun spending in at least 39 congressional races where they haven’t previously deployed money this cycle, a Reuters review of spending by some of the largest Republican political groups shows.

Many of the candidates receiving new support sit in Republican strongholds and are still running ahead of Democratic opponents in public polls, these people said, indicating rising worry among party leaders over whether voters will use the November 3 election to air dissatisfaction over US President Donald Trump’s policies.

House Republican leaders recently warned dozens of campaigns that the party’s internal data shows that they cannot assume they will win, even if they are currently ahead in public polls and represent districts Trump won by double digits, two of the people said.

“Republicans are playing defence in some of the strongholds that they’re used to not having to worry about,” said Republican strategist Ron Bonjean, a partner at bipartisan public affairs firm Rokk Solutions.

Republicans currently hold a narrow 218-214 majority in the House, with one independent caucusing with Republicans and two vacancies. Democrats would need to net at least four seats in the midterms to take control of the chamber next year.

Two Republican operatives working with party leaders said they’re using their larger spending power to stifle Democrats before they have a chance to attack. They said the party was taking out “insurance policies” to ensure Republican-held districts remain in the party’s hands.

“Republicans are deploying our massive war chest to drive voters to the polls and supercharge our candidates,” said Natalie Baldassarre, national press secretary for the Republican National Committee. “We’re not taking anything for granted, because, unlike Democrats, Republicans aren’t throwing in the towel on races we can win.” Republican congressman Bryan Steil is one telling example. His Wisconsin district voted for Trump by about 4.5 percentage points in 2024 and is rated “lean Republican” by Cook Political Report. Still, conservative super PACs dumped US$1.5 million on his race this month, their first investment of this election cycle. A representative for Steil declined to comment.

In North Carolina’s 3rd Congressional District east of Raleigh, Congressman Gregory Murphy this month received US$131,107 from a conservative PAC a week ago – the first outside spending on his behalf in the midterms. Democrats have spent over US$326,000 trying to oust him since July. Trump won the district by 14 percentage points and Cook rates it “solid Republican”. Murphy’s office didn’t return a request for comment.

The emergency deployments reflect a harsh reality: economic strain is battering traditionally Republican strongholds. Rising fuel prices, energy costs and fertiliser expenses are hitting voters in the agricultural heartland particularly hard.

One Republican House campaign aide said the environment for candidates in Iowa, Kansas and other Midwest states was “dire” as diesel prices soar.

“We’re in this crucial period in the last 30 days where candidates have to really make a case, given how tough the headwinds are,” said Kevin Madden, who advised former Republican presidential candidate Mitt Romney and is now senior partner at corporate advisory firm Penta Group. Campaigns are running as if they are behind in the polls “even in red districts or traditionally safe” ones, Madden said.

More than US$1.56 billion, overall, has been spent by independent committees on federal elections so far, with roughly US$496 million deployed just since Labour Day, according to a Reuters analysis of super PAC spending. That figure does not include all spending by dark money nonprofits that do not disclose their donors.

Republicans have reserved at least US$888 million in advertising over the coming weeks, compared to at least US$666 million for Democrats, according to AdImpact, which tracks political advertising. No Going Back PAC, which is fully funded by Trump’s super PAC MAGA Inc., is leading the surge, Federal Election Commission records show.

“That’s the advantage of having a s* tonne of money,” said one Republican operative working on Trump’s midterm strategy. “We’re not going to let Democrats take free shots on goal.” Over the last three weeks through Friday, Republican-leaning super PACs have outspent Democrats by almost 2-to-1, showering races with roughly US$309.7 million since Labour Day compared with US$174.2 million going to help Democratic candidates, the FEC data shows.

“Republicans have air superiority. House Democrats are scrambling to catch up with the very limited resources they have,” said Mike Marinella, national press secretary for the National Republican Congressional Committee, which works to elect Republicans to the House.

Democrats acknowledge their funding disadvantage but say the Republican push to spend money on districts that Trump won easily reflects the trouble the party faces in the midterms.

“Republicans are running scared, know they’ve lost the American people, and are trying one last hail mary to spend their way out of certain defeat,” said Viet Shelton, spokesman for the Democratic Congressional Campaign Committee.

In one district in south Texas that Trump won by 18 percentage points in 2024, Republican groups have pumped about US$2 million into text messages, direct mail and digital ads since September 5 to help incumbent congresswoman Monica De La Cruz keep her seat. Cook Political Report moved her seat from “lean Republican” to “toss-up” on Friday.

De La Cruz is grateful for her supporters helping defeat her rival, her campaign manager said, when asked about the money spent by her Republican backers.