WASHINGTON — Republicans on Capitol Hill are using President Biden’s failures to fuel their bid to retake control of Congress, focusing on his collapsing legislative agenda, his unfulfilled promise to “shut down” the coronavirus pandemic and rising voter anxieties over school closures and inflation as they seek a winning message for this year’s elections.

Mr. Biden’s troubles have frustrated Democrats, prompting calls for a major course correction. At the same time, they have delighted Republicans, who have been intent on rehabilitating themselves in the eyes of voters after the Jan. 6 attack on the Capitol last year, which highlighted the party’s lurch toward extremism and its continuing rifts under the influence of former President Donald J. Trump.

Now, after months of grappling with their party’s role in stoking the riot, the ongoing influence of Mr. Trump’s election lies and the rise of right-wing activists who risk alienating more mainstream conservative voters, Republicans believe they are finally in a position to capitalize on what they view as a historically advantageous environment.

Many Republicans say they see no need for any course correction — or to put forward a positive agenda in an election year they say will boil down to a referendum on Mr. Biden.

“I’ll let you know when we take it back,” Senator Mitch McConnell, Republican of Kentucky and the minority leader, said at a news conference this month when asked what his party’s agenda would look like if it won control of Congress. He added, “The election this fall is a referendum on this all-Democratic government.”

With inflation at a 40-year high, Republicans have spotlighted so-called kitchen-table issues like rising gas and home heating costs. They have sought to undermine Mr. Biden’s most ambitious policy proposals as “reckless spending,” and they have gloated as Democrats have been unable to hold together to push them through. And they have highlighted the administration’s foreign policy setbacks, like the chaotic withdrawal from Afghanistan, in an effort to uncut Mr. Biden’s competence in the eyes of voters.

“They’ve been like a bass drum in a band — it’s going on all the time,” Josh Holmes, a political adviser to Mr. McConnell, said of the Republicans and their stream of critiques. “Leadership has never gotten off on a tangent of talking about the 2020 election. They’ve been entirely forward-looking.”

The message discipline could be foiled as the campaign season intensifies and Republican candidates seeking Mr. Trump’s endorsement embrace his false claims about the 2020 presidential election being stolen. Mr. Trump has already denounced Republican lawmakers by name for voting to impeach him and to pass Mr. Biden’s $1 trillion infrastructure plan.

“They can try to hide and distract from Tump as much as they want, but the reality is you have a former president who is hitting the campaign trail twice a month,” said Xochitl Hinojosa, a Democratic strategist and former communications director for the Democratic National Committee. “He’s still out there, and he says crazy things and gets coverage.”

Chris Meagher, a White House spokesman, said Republicans were “rooting for inflation and don’t have a plan to address price increases for working families.” He added, “They don’t have a plan to beat back the pandemic or to grow jobs.”

For Republicans, the biggest political fear is that they may be peaking too soon. In private meetings, some have raised the question of whether voters will still blame Mr. Biden for the prolonged pandemic in the fall if the Omicron wave subsides and supply chain issues dissipate.

But for now, with Mr. Trump out of office and Mr. Biden struggling to energize the voters who elected him, Republicans are feeling optimistic.

They have expressed glee over the decision by Democrats to take up voting rights legislation in a midterm election year, an ultimately losing legislative fight that left senators in the majority party struggling to explain arcane filibuster rules, while Republicans focused on more tangible topics like the price of a gallon of milk.

“If I had one wish, it would be that the election would be today, because the political environment is so good for us,” said Richard Walters, the chief of staff for the Republican National Committee, pointing to Mr. Biden’s declining approval rating, which this month hit 41 percent in a Pew Research Center survey.

Republican strategists note with optimism that no president in the past 70 years has ever improved his approval rating substantially after late January of a midterm election year. And while nominating a Supreme Court justice to succeed Justice Stephen G. Breyer offers Mr. Biden an opportunity to energize crucial Democratic constituencies, Republicans were quick to shrug it off given that it would not change the court’s conservative tilt.

Republicans have single-mindedly kept the focus on Mr. Biden.

In the House, Representative Kevin McCarthy, Republican of California and the minority leader, has worked to keep his more incendiary members out of the news — with mixed success — and hammered away at the president.

He has also tried to lay out what Republicans would do if they won control, releasing a “Parents Bill of Rights” that would give parents more say in their children’s curriculum and drawing up a list of investigations the House would open to scrutinize the Biden administration. He recently sought advice from former Speaker Newt Gingrich, whose “Contract With America” in 1994 encapsulated the Republican message as the party campaigned successfully to win control of the House that year.

Mr. Gingrich, whose meeting with Mr. McCarthy was reported by The Washington Post, recently said on Fox News that if Republicans won this year, members of the House committee investigating the Jan. 6 attack could be jailed.

In the Senate, Republican leaders have used regular news conferences, often attended by a majority of their members, as what they call “plug-and-play forums” to speak directly to voters at home about Mr. Biden and his party.

“The role I see of the minority is to point out the fact that his administration is ignoring the needs of the American people,” Senator John Barrasso of Wyoming, the No. 3 Republican, said in an interview.

Mr. Barrasso said the concerns he had heard from constituents over this week’s recess had been left unaddressed in Washington.

“Heating costs are up, grocery costs are up, and you have a president talking about spending all of this additional money and focusing on voting,” he said. “People asked me 23 different things, and voting ended up dead last.”

Some lawmakers and top Republican strategists argue that with Mr. Biden’s numbers sagging and his policies floundering, he is doing their job for them.

“When your opponents are hanging themselves, don’t cut the rope, and that’s what we see the Democrats doing here,” said Jeff Roe, the founder of Axiom Strategies, a political consulting firm that has worked for Gov. Glenn Youngkin of Virginia and Senator Ted Cruz of Texas, both Republicans. “All we need to do is stay out of the way.”

Republicans on Capitol Hill point to the withdrawal from Afghanistan last summer — a tumultuous period during which a suicide bombing at the Kabul airport killed 13 U.S. service members — as the turning point for a once-popular administration. Internal Republican polls showed Mr. Biden losing six percentage points in his approval rating at that time, a decline that he has not managed to reverse.

“Republicans have a lot of significant, deep problems, but Democrats have been so bad that it made it really easy to overlook them,” said Brendan Buck, a former adviser to the past two Republican speakers of the House, Paul D. Ryan and John A. Boehner. Republicans are still dealing with the culture wars and populism that may pose serious long-term demographic challenges, he said, but for now the Democrats have overshadowed those fissures.

Mr. McCarthy, who is in line to be speaker if Republicans win the House, has been increasingly bullish about the prospect, predicting that 70 Democratic-held seats will be competitive.

There are some bright spots for Mr. Biden. Democrats view his opportunity to appoint a Supreme Court justice as a chance for a change in focus and a moment for him to claim a high-profile victory. Mr. Biden has highlighted the 3.9 percent unemployment rate as part of the recovery he promised to Americans, and his top aides have underscored that he has overseen the strongest economic growth in decades.

The Senate map for Democrats is also somewhat favorable; Mr. Biden won a majority of the battleground states with Senate races that are likely to decide control of the chamber.

Ms. Hinojosa said Democrats must spend heavily in competitive states to tell voters the story of Mr. Biden’s accomplishments.

“The White House realizes that and there’s a better-coordinated effort to do that than there has been in the past,” she said. “They’re just going to need to do it more aggressively.”

But some Republicans believe it will be difficult for Mr. Biden to improve his standing.

“The left is disappointed with him and the anti-Trump Republicans and independents thought they were going to get a moderate governing,” said Whit Ayres, a veteran Republican pollster. “I don’t know how resolving the pandemic is going to affect that fundamental reality that he is completely misplaying his hand.”