WASHINGTON US President Joe Biden will return to the campaign trail next week after isolating from mild Covid symptoms, the head of his reelection campaign said on Friday, saying the Democrat was staunchly committed to defeating Republican Donald Trump.

"He is absolutely in it," Biden campaign chair Jen O'Malley Dillon told MSNBC in an interview. "We have to take seriously the concerns that people are expressing, but the way to get past them is to get back to the business of beating Donald Trump."

O'Malley Dillon also said that Biden would be endorsed by a "significant national organisation" but gave no other details.

"We've definitely seen some slippage in support, but it has been a small movement," she said. Biden has grassroots support and is committed to working to continue to reassure voters, especially in battleground states in what is going to be a close election, she added.

"He's got to show that he is fighting for the American people," O'Malley Dillon told MSNBC.

  - Reuters