LAS VEGAS — US President Joe Biden faces new questions over his candidacy in the November election — with his campaign events currently on pause due to a Covid-19 infection.

The top two Democrats in the US Congress, Senate Majority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries, are both reported to have met him individually to express concerns over his bid for the White House.

Nancy Pelosi, the former House Speaker, has also privately told him that he cannot beat Donald Trump in November's election, according to CNN.

Biden’s re-election attempt was already being buffeted by growing dissent among top Democrats after his disastrous debate performance against Donald Trump last month.

Announcing his Covid infection on Wednesday, Biden's press secretary said the 81-year-old was facing mild symptoms.

He would isolate at his home in Delaware while carrying out "all of his duties fully", said Karine Jean-Pierre. She added that the president was vaccinated and boosted. He has tested positive for Covid twice before.

Biden was seen earlier in the day visiting supporters in Las Vegas and speaking at an event. He was forced to cancel a speech later in the day at UnidosUS, a Latino civil rights organization.

It marked a sudden and debilitating end to a trip that was supposed to see Biden hitting the campaign trail again with full force — after the pause sparked by the attempted assassination of his rival Trump.

The president had spent time in Las Vegas trying to revive his appeal among Hispanic voters, with whom his poll lead has slipped since 2020.

Later on Wednesday, he was seen moving slowly and cautiously up the steps to Air Force One. He was not wearing a mask. As he boarded the plane, he was heard to say: "Good, I feel good."

Biden has faced growing calls to withdraw from the election race in recent weeks.

During their separate private meetings with Biden which took place last week, Schumer and Jeffries expressed concerns that his presence at the top of the November election ticket could hurt their chances for controlling either chamber in Congress, according to multiple reports.

After the reports, White House spokesman Andrew Bates said: “The president told both leaders he is the nominee of the party, he plans to win, and looks forward to working with both of them to pass his 100 days agenda to help working families."

A spokesman for Jeffries said, "it was a private conversation that will remain private". Schumer's office called the reporting "idle speculation" but added the Democratic leader "conveyed the views of his caucus directly to President Biden".

Ms Pelosi, too, is said by CNN to have told the president in a recent conversation that polling suggested he could harm the Democrats' chances of winning the House in November.

The president pushed back, at which point Ms Pelosi asked for input on key data from the president's long-time adviser, according to CNN, which cited four sources briefed on the call.

It is not clear when the conversation took place. Ms Pelosi's office told CNN she had not been in touch with the president since Friday.

About two dozen Democratic politicians have publicly called for Biden to step aside in recent weeks, including Adam Schiff, a congressman from California who has called on Biden to "pass the torch".

Schiff said Biden "has been one of the most consequential presidents in our nation’s history", and he could "secure his legacy of leadership" by allowing another Democrat to step forward.

In an interview with BET, Biden said he did not feel he could pass the mantle with the country so "divided".

The president also said, for the first time, that he would consider dropping out of the race if any of his doctors said he had a "medical condition".

Before the announcement of Biden's infection on Wednesday, reporters on the Las Vegas trip said they had been rushed off the site of a campaign stop at a Mexican restaurant to the city's airport following the announcement.

The restaurant had been ablaze with color, with Mexican art and guitars hanging from the walls and banners draped from the ceiling. One wall was adorned with “Biden-Harris” posters.

As ceiling fans swirled on low speed and Latino pop played quietly from the speakers, Biden walked in via the kitchen door — which was flanked by a Secret Service detail — and entered a main dining area.

He shook hands with diners — who had clearly been prepared some time in advance for his arrival — kissed one and had selfies taken with others.

The president seemed somewhat stiffer and appeared slower than the day before, when he had given an energized performance in a speech to a national civil rights group.

Commenting later in the day on his Covid infection, the president's doctor Kevin O'Connor said Biden had presented with upper respiratory symptoms, including a runny nose and a cough, and had been given his first dose of Paxlovid.

He felt fine during his first event of the day but later tested positive, Dr O'Connor said.

Biden posted on X to thank everyone for "the well wishes" and said he would "work to get the job done for the American people" while in recovery.

In another post on his account, he stated: "I'm sick" before going on to write "... of Elon Musk and his rich buddies trying to buy this election. And if you agree, pitch in here".

The tweet pointed to a donations portal. — BBC