Two Trump-backed Republicans won special congressional elections in Florida on Tuesday, according to The Associated Press, shoring up their party’s slim majority in the House at a crucial moment for President Trump’s domestic agenda.
Jimmy Patronis, the state’s chief financial officer, won the race to replace Matt Gaetz in the First Congressional District, on the western end of the Panhandle. With most of the vote counted late Tuesday, Mr. Patronis had won 57 percent.
And State Senator Randy Fine captured the Sixth District seat that had been held by Michael Waltz, now Mr. Trump’s national security adviser. That district is rooted in Daytona Beach and parts of the northeast coast. Mr. Fine had 56.7 percent of the vote as of 9 p.m.
Both seats had been expected to remain in Republican hands, though some private polls showed Mr. Fine facing a close contest against Josh Weil, his Democratic opponent. Mr. Weil and Gay Valimont, the Democrat who ran against Mr. Patronis, each raised millions of dollars for their campaigns despite the Democrats’ struggles in Florida.
Mr. Gaetz resigned from his House seat last year after Mr. Trump nominated him to be attorney general. He later withdrew from consideration for that post, amid an ethics investigation into allegations of sexual misconduct and drug use.
Both Mr. Patronis and Mr. Fine cleared their respective primary fields easily after securing Mr. Trump’s endorsement. Mr. Trump won both districts by double-digit margins in November.
Even so, as the special election on Tuesday drew near, some Republicans voiced concern about Mr. Fine’s race. Steve Bannon, a top ally of Mr. Trump, warned on his show “War Room” that “we have a candidate that I don’t think is winning.”
Gov. Ron DeSantis, a Republican who represented the Sixth Congressional District before running for statewide office, predicted that “it’s going to be a way underperformance” for his party, compared with previous elections.
Yet the race was called by The Associated Press just half an hour after the polls closed, as Republican elected officials and supporters of Mr. Fine were still ordering from a food truck at The 2A Ranch in Ormond Beach, Fla., where his campaign was holding a watch party.
They celebrated the results inside a barn decorated with hundreds of pieces of Trump memorabilia, including flags, dozens of paintings of Mr. Trump and life-size mannequins.
“Mr. President, this win is yours far more than it is mine,” Mr. Fine declared.
Mr. Fine’s margin — about 14 points with nearly all of the votes counted as of 9 p.m. — was less than half of Mr. Waltz’s in November. Mr. Weil, in a statement after the results, called it “an incredible gain” for Democrats and “a warning sign” to Mr. Trump and his allies that voters would not support cuts to health care programs and Social Security, among others.
The Democratic National Committee pointed to Mr. Patronis’s similar margin in the Panhandle district, one of the most conservative in the state, as evidence that “the momentum is on our side.”
Ken Martin, the chairman of the D.N.C., said of Mr. Patronis’s Democratic opponent: “Her massive overperformance” in a district that Mr. Trump won by 37 percentage points last fall “is the best performance for Democrats in the district this century and spells trouble for Republicans everywhere.”
Mr. Fine, a former gambling lobbyist and pugnacious state representative, is the only Jewish Republican in the Florida Legislature. He broke with the governor when he endorsed Mr. Trump instead of Mr. DeSantis in the Republican presidential primary last year, saying he thought that Mr. Trump would be a better ally against antisemitism.
“No one is better positioned to take up the mantle for Florida families, small business owners and workers,” Maureen O’Toole, a spokeswoman for the House Republican campaign arm, said of Mr. Fine.
Mr. Patronis, she said in a separate statement, will be “a strong voice for Floridians with our Republican majority in Congress.”
With control of the House teetering, restoring Republican votes for the two vacant seats will be important as the party navigates internal divisions over a domestic policy package, which is expected to include significant cuts to spending and taxes. Democrats are expected to unanimously oppose the plan, meaning that House Republicans can barely spare any votes.
With the outcomes of the two races on Tuesday, there will now be 220 Republicans and 213 Democrats in the chamber, with two vacancies still to be filled in Arizona and Texas.
Republican concerns about their narrow margin of control in the House — and about Mr. Fine’s race in particular — grew to the point that on Thursday, Mr. Trump asked Representative Elise Stefanik of New York to withdraw her name from consideration to be ambassador to the United Nations, and to remain in Congress instead.