He has not been invited to meet Mr Biden yet, but asked whether he wanted the president to beat Donald Trump in next year’s election, he said: “It’s clear what my desired outcome would be.”
Speaking to Politico’s Power Play podcast, Sir Keir also said: “I feel very strongly that since Brexit, there’s been a sense that we’ve not just exited the EU, that we’ve somehow turned our back on the world and wherever you go people feel almost the absence of the UK, once a leading voice, now rarely consulted.”
The revelation comes before a meeting in Paris between Sir Keir and French president Emmanuel Macron.
The Labour leader also spent the weekend in Montreal at a conference for left-wing leaders hosted by Canadian PM Justin Trudeau and attended by former New Zealand PM Jacinda Ardern and former Finnish leader Sanna Marin.
As Sir Keir’s 15-20 point poll lead over Rishi Sunak gives him increasing confidence, he has pledged to rewrite the UK’s Brexit deal if Labour wins the next election, with hopes of a closer trading relationship with the EU.
He said he will begin talks with Brussels in 2025 if he makes it to Number 10, saying he “owes it to his children”.
“Almost everyone recognises the deal Johnson struck is not a good deal – it’s far too thin,” Sir Keir told the Financial Times on Sunday.
“As we go into 2025 we will attempt to get a much better deal for the UK.”
Downing Street hit back on on Monday, saying Britain’s trade deal with the EU does not need to be renegotiated. Mr Sunak’s official spokesman described it as “the world’s largest zero tariffs zero quota deal”.
The spokesman added: “We are not looking to relitigate the past or reopen it in any way, shape or form.
“There is a set statutory review period, but beyond that we are very much focused on maximising the opportunities it presents for the public.”
Sir Keir also told the podcast Britain needs to “wean itself off” China “when it comes to trade, commerce and technology”.
He said: “We need to be absolutely clear about the security of the UK and issues like spying and interference which goes on and of course the human rights abuses that are taking place.”