Joe Biden has claimed that too much international travel was the reason for his disastrous performance in the first US presidential debate with Donald Trump last week. The 81-year-old Democrat’s campaign previously attributed his poor showing to a cold and misguided preparation by his aides.

During the CNN-hosted 90-minute faceoff against his Republican rival, the incumbent US president appeared visibly frail and confused, with his answers marred by awkward pauses and numerous inaccurate statements.

Most commentators, both Republican and Democrat, have concurred that Trump came out on top in the debate. A poll by CBS News/YouGov shortly after the event found that 72% of registered voters do not believe that Biden has the “mental and cognitive health necessary to serve as president.”

Several media outlets have claimed that top-level Democratic donors are now pushing for Biden to be replaced as the party’s candidate ahead of the November 5 vote. Multiple reporters and at least one Democratic lawmaker have openly urged the president to bow out of the race.

Addressing his supporters at a fundraiser in McLean, Virginia on Tuesday, Biden said: “I wasn’t very smart. I decided to travel around the world a couple of times… shortly before the debate,” as quoted by Politico.

The US leader regretted not listening to his staff, adding that he ended up almost falling "asleep on stage” as a result.

In early June, the US president attended the D-Day commemorations in France, before heading for a G7 meeting in Italy on June 12. Biden subsequently flew to a fundraiser in Los Angeles, returning to Washington DC 11 days before the debate. During this time, the Democratic hopeful was reportedly actively preparing for the encounter with Trump, with several aides arranging rehearsals.

Shortly after the debate, First Lady Jill Biden suggested during a fundraiser that her husband was not feeling well during the event, insisting, however, that his poor showing should not eclipse his term in office as a whole.

Late last month, Axios, citing an anonymous person close to Biden, alleged that his team had chalked the president’s flop up to him being “over-prepared and relying on minutiae when all that mattered was vigor and energy.” His campaign supposedly blamed Biden’s aides for preparing him for the “wrong debate.”

Around the same time, CBS News quoted an unnamed senior official as saying that Biden had a cold, hence his raspy voice during the debate.

Meanwhile, campaign spokesperson Seth Schuster has insisted that Biden is not dropping out of the race.