WASHINGTON — President Joe Biden forcefully tried Friday to quell Democratic anxieties over his unsteady showing in his debate with former President Donald Trump, as elected members of his party closed ranks around him in an effort to shut down talk of replacing him atop the ticket.

Biden’s halting delivery and meandering comments, particularly early in the debate, fueled concerns from even members of his own party that at age 81 he’s not up for the task of leading the country for another four years. It created a crisis moment for Biden’s campaign and his presidency, as members of his party flirted with potential replacements, and donors and supporters couldn’t contain their concern about his showing against Trump.

Biden appeared to acknowledge the criticism during a rally in Raleigh, North Carolina, saying “I don’t debate as well as I used to.” But “I know how to do this job. I know how to get things done.” Speaking for 18 minutes, Biden appeared far more animated than his showing the night before, and he excoriated Trump for his “lies” and campaign aimed at “revenge and retribution.”

“The choice in this election is simple,” Biden said. “Donald Trump will destroy our democracy. I will defend it.”

He added, alluding to his candidacy: “When you get knocked down, you get back up.”

Even before the debate, Biden’s age had been a liability with voters, and Thursday night’s faceoff appeared to reinforce the public’s deep-seated concerns before perhaps the largest audience he will garner in the four months until Election Day.

Privately, his campaign had spent the previous hours working to tamp down concerns and keep donors and surrogates on board. Democratic lawmakers acknowledged Biden’s poor showing, but tried Friday to stop talk of replacing him as their standard-bearer, and instead tried to shift the focus onto Trump’s attacks and falsehoods that they hoped would remind voters of the daily turbulence of his presidency.

“Well, the president didn’t have a good night, but neither did Donald Trump with lie after lie and his dark vision for America,” North Carolina Gov. Roy Cooper said Friday, hours before he introduced the president in Raleigh. “We cannot send Donald Trump back to the White House. He’s an existential threat to our nation.”

Former President Barack Obama backed up his former vice president, posting on X: “Bad debate nights happen.” Alluding to his own poor showing in the first debate of his reelection campaign in 2012, Obama continued: “Trust me, I know. But this election is still a choice between someone who has fought for ordinary folks his entire life and someone who only cares about himself.”

House Democratic leader Hakeem Jeffries answered with a flat “no” when asked Friday if Biden should step aside.

Biden’s campaign billed the Raleigh event as the largest-yet rally of his reelection bid in the state Trump carried by the narrowest margin in 2020. He’ll then travel to New York for a weekend of big-dollar fundraisers that his campaign needs more than ever.

Biden’s campaign announced that it raised $14 million on debate day and the morning after, while Trump’s campaign said it raised more than $8 million from the start of the debate through the end of the night.

Vice President Kamala Harris, whom the Biden campaign sent out to defend his performance, tried to reassure Biden supporters at a rally Friday in Las Vegas.

“This race will not be decided by one night in June,” she said. “This race will be decided by you, by us. Who sits in the White House next year will be determined by what we together do in these next 130 days.”

Rep. James Clyburn, D-S.C., whose support in that state helped Biden secure the Democratic nomination four years ago, said he would likely speak to Biden later Friday and his message would be simple: “Stay the course.”

Biden and his team have long wagered that voters would look past their concerns about his age and unpopularity when confronted at the ballot box by a choice between the president or Trump. Despite their concerns about Biden’s performance, they sought to find solace in Trump doing little to expand his own appeal to voters Thursday.

Polls from CNN and 538/Ipsos conducted soon after the debate found that most debate-watchers thought Trump outperformed Biden. But the men’s favorability ratings remained largely unchanged, just as they did in the aftermath of Trump’s conviction.

Democrats seized on Trump’s equivocations on whether he would accept the will of voters this time around; his refusal to condemn the rioters who stormed the Capitol on Jan. 6, 2021, trying to overturn his 2020 loss to Biden; and his embrace of the conservative-leaning Supreme Court’s overturning of Roe v. Wade that had legalized abortion nationwide.

Trump, meanwhile, flew to his golf club in Virginia, a onetime battleground that has shifted toward Democrats in recent years but that his aides believe can flip toward the Republicans in November. He was set to hold at rally Friday afternoon in Chesapeake.