U.S. President Joe Biden attends the first presidential debate hosted by CNN in Atlanta, Georgia, U.S., June 27, 2024. / REUTERS/Marco Bello/File Photo

President Joe Biden's allies scrambled on june28 to contain the damage from a feeble debate performance with Republican rival Donald Trump that prompted some of his fellow Democrats to wonder whether they could replace him as their candidate for the November U.S. election.

Biden's verbal stumbles and occasionally meandering responses in the debate heightened voter concerns that the 81-year-old incumbent might not be fit to serve another four-year term.

Hakeem Jeffries, the Democratic Party leader in the U.S. House of Representatives, avoided answering directly when asked if he still had faith in Biden at the top of the ticket. “I support the ticket. I support the Senate Democratic majority. We're going to do everything possible to take back the House in November. Thank you, everyone,” he told reporters.

Other Democrats said they would assess their options in the days to come. Asked if they should look for another nominee, Representative Jim McGovern said: "I haven't come to any conclusion yet."

The Biden campaign said it raised $14 million on June 27 and June 28  and posted its single best hour of fundraising immediately after the Thursday night debate. The Trump campaign said it raised $8 million on the night of the debate.

Biden, already the oldest American president in history, faced only token opposition during the party's months-long nominating contest, and he has secured enough support to guarantee his spot as the Democratic nominee for the Nov. 5 election.

Former President Trump, 78, likewise overcame his intra-party challengers early in the year, setting the stage for a long and bitter general election fight.

Three columnists from the New York Times' left-leaning opinion section called on Biden to drop out of the race.

One Biden donor, who asked for anonymity, called his performance "disqualifying" and predicted that some Democrats would revisit calls for him to step aside. That would give the party time to pick another nominee at its national convention, which starts on Aug. 19. 

Democratic officials played down that possibility.

"It's not likely to happen," Biden campaign co-chair Mitch Landrieu said on CNN. 

One campaign staffer, speaking on condition of anonymity, said they were frustrated by Biden's performance and hoped it would prompt top strategists to re-think their approach.

But other aides and allies said privately they did not think the blowback would threaten his chances of winning the nomination. 

Former House Speaker Nancy Pelosi and other senior Democrats - including possible replacements like California Governor Gavin Newsom - said they were not abandoning Biden.

"Stay the course. Chill out," Representative Jim Clyburn said.

A BAD NIGHT FOR BIDEN, UNDECIDED VOTERS SAY

Interviews with undecided voters confirmed that it was a bad night for Biden. They described his showing as feeble, embarrassing and difficult to watch.

The Trump campaign released a video on Friday highlighting Biden's stumbles. "Last night the world saw who he is. He is unfit to serve," spokeswoman Karoline Leavitt said.

One Republican adviser, speaking on condition of anonymity, said the debate would help them compete in Democratic-leaning states like Virginia and Minnesota.

Trump fundraisers said they were fielding enthusiastic calls from donors. "Anyone who raises money knows there's a time to go to donors, and this is one of those watershed moments," said Ed McMullen, who served as ambassador to Switzerland during Trump's presidency.

As Trump supporters lined up hours ahead of a rally in Virginia, some said they were struck by Biden's poor performance. “I’m scared they are going to replace him and put up somebody more competitive,” said Mike Boatman, who said he had attended more than 90 Trump rallies.

Questions about Trump's fitness for office have arisen also over his conviction last month in New York for covering up hush money payments to a porn star, his efforts to overturn the 2020 election and his chaotic term in office. 

But despite a litany of falsehoods and deflections from Trump during the debate, the focus afterwards was squarely on Biden.

The 90-minute debate at CNN headquarters in Atlanta took place more than four months before the election. That could mitigate the damage for Biden, as the memory of his performance fades and news events generate fresh headlines.

Trump, for instance, is scheduled to be sentenced in New York on July 11, just days before his party convenes to formally nominate him. He still faces three other criminal indictments, though none appears likely to reach trial before November.

At a Waffle House restaurant in Atlanta after the debate, Biden told reporters he did not have concerns about his performance. "It's hard to debate a liar," he said.

Biden was headed for a Friday rally in Raleigh, North Carolina, a state that Democrats hope to win back from Republicans this November, before flying to New York for a fundraiser and the opening of a monument dedicated to the 1969 Stonewall riot for LGBT rights.