President Joe Biden blamed jet lag for his poor performance last week, telling reporters it was “not smart” for him to “go around the world a couple of times” before the debate.
“I didn’t listen to my staff… and then I almost fell asleep on stage,” he said.
Mr. Biden, 81, last returned from a business trip on June 15, nearly two weeks before the June 27 debate.
Biden’s comments come amid panic within the party ahead of November’s election over his mental health, and after a Texas congressman became the first sitting Democratic lawmaker to call for his resignation following his debate performance.
“I hope he makes the painful and difficult decision to step aside,” Rep. Lloyd Doggett said in a statement Tuesday.
President Biden appeared to struggle to come up with some responses during his debate with former President Donald Trump last Thursday.
“It’s not an excuse, it’s an explanation,” he said at a private fundraiser in Virginia on Tuesday night, referring to his trip.
He also apologized for his record and said it was “very important” that he win re-election, according to ABC News.
Mr Biden made two separate trips to Europe in the space of two weeks last month.
On June 15, he appeared at a fundraiser with former President Barack Obama after an overnight trip from Italy. He returned to Washington DC the following day.
White House officials previously said Mr Biden had a cold on the day of the debate.
The president did not mention any illness during his remarks on Tuesday. A White House spokesman said earlier in the day that he did not take any cold medicine during the debate.
Mr Biden also spent six days at Camp David, the presidential retreat outside Washington DC, to prepare for the debate with Mr Trump.
The New York TimesCiting an unnamed source familiar with Mr. Biden’s schedule, the newspaper reported on Tuesday that his workday begins at 11 a.m. each day and that he is given time to nap each day.
The paper also reported that he was so exhausted from the trip that his debate preparations were cut short by two days to allow him time to rest at his beach house in Delaware.
Andrew Bates, a spokesman for Mr Biden, said the president started “working out well before” 11am, after his workout, during his stay at Camp David.
His age has been a controversial issue in this election, with In many polls, voters say he is too old to do the job effectively.
Mr. Biden is currently the Democratic Party’s most promising candidate for President.
He vowed to continue the race regardless of performance debate.
In a statement Tuesday, Rep. Doggett, 77, said the debate reinforced his decision to urge Mr. Biden to resign.
“Instead of reassuring voters, the President has failed to effectively defend his accomplishments and debunk Trump’s many lies,” said Rep. Doggett, who was sworn into office in 1995 and is running for re-election.
He said there were too many risks if the president lost to Trump because of age concerns.
“While much of his work is transformational, he has committed to being a transitional person,” the senator said of Mr. Biden.
“He has the opportunity to encourage a new generation of leaders who can choose candidates to unify the country through an open, democratic process.”
“My decision to go public with these strong doubts was not an easy one, nor does it diminish my respect for all that President Biden has accomplished,” Rep. Doggett said.
Biden will have a prime-time interview with ABC News’ George Stephanopoulos on Friday, his first since the debate.
Several prominent Democratic lawmakers voiced concerns about Biden’s age and stamina this week, but none spoke up until Rep. Doggett called on him to drop his candidacy.
Other senior Democrats have acknowledged concerns about Mr Biden’s chances of winning but stressed that the decision to leave the race was the president’s alone.
Many flocked to the liberal-leaning television channel MSNBC to defend him.
Former US House Speaker Nancy Pelosi told MSNBC on Tuesday that “Joe Biden is going to have to decide” to do what he thinks is best.
One of President Biden’s most prominent supporters, South Carolina Congressman Jim Clyburn, said he would back Vice President Kamala Harris as the party’s nominee if Biden steps down.
But he told the network: “I want this ticket to continue to be Biden-Harris.”
Rep. Jamie Raskin, a Democrat from Maryland, told MSNBC this weekend that the debate created a “difficult situation.”
He acknowledged that there were “very honest, serious and rigorous conversations going on at every level of our party.”
But he added: “Whatever President Biden decides, our party will remain united and the party needs him to be at the center of our campaign discussions.”
