A Democrat senator has broken ranks to say that Joe Biden cannot beat Donald Trump in the November election.

Michael Bennet, a senator for Colorado, told CNN on Tuesday that Trump “is on track to win this election – and maybe win it by a landslide and take with him the Senate and the House”.

Asked whether the US president should stand aside, Mr Bennet, while not explicitly calling on him to stand aside, said: “We should be having a discussion. This is something for the president to consider,”

Mr Bennet is the first Democrat in the Senate to break with the president publicly.

Democrats in Congress have been deeply divided over whether to fall in line behind Mr Biden’s wounded re-election campaign or urge him to step aside because of persistent questions about his health and acuity.

Seven Democrats in the House of Representatives have publicly asked the president to end his re-election bid. Mr Biden has repeatedly said he is staying in the race.

The president’s halting June 27 debate performance against Trump and low public approval have raised fresh doubts about his ability to win the Nov 5 election or to keep up with the demands of his gruelling job for another four years.

Many Democrats have expressed worries that Mr Biden has not done enough to convince voters that the debate was an aberration, rather than a true reflection of his abilities.

Democratic Senate majority leader Chuck Schumer brushed off questions about Mr Biden’s fitness, saying: “I’m with Joe” during an exchange with reporters after Senate Democrats met to discuss the president’s campaign.

Some Democrats have expressed frustration that the party was focused on Mr Biden’s shortcomings rather than unifying against his Republican rival.