Sir Keir Starmer revealed that he speaks to Barack Obama as he continued his tour of meeting world leaders.
The Labour leader made the remarks during the latest stage of his world tour, where he has sought to burnish his image on the international stage.
Having met Canadian premier Justin Trudeau, along with other Left-wing leaders at a summit in Montreal, he will hold talks with French president Emmanuel Macron on Tuesday.
He also appears to be eyeing up a meeting with Joe Biden, the US president, whose “Bidenomics” and landmark green subsidy push have won Labour’s admiration.
Speaking to Politico’s Power Play podcast, Sir Keir said his team were in talks with the Biden administration but admitted he had not yet been invited to meet the American leader.
Mr Obama, the 44th US president, was seen as the most progressive American leader in decades. He served two terms before Donald Trump seized victory for the Republicans in 2016.
Mr Biden has confirmed he will run for a second stint in the White House in 2024, when his likeliest challenger will be Donald Trump once again as the Republican front-runner.
On the 2024 election, Sir Keir said: “It’s clear what my desired outcome would be, but the desired outcome may yield to a different outcome.”
The Labour leader used his trip to Canada to stress the importance of British border security.
He said: “In principle it’s wrong to think that control of the border is not a progressive issue.
“Because if you lose control of the border, a number of things happen – that’s when in certain places you get into the business of people talking about walls and fences because you’ve lost control of the border.
“It goes down this slippery slope. And if you can’t have a wall and a fence, you have some of the gimmicks that we’re seeing in the United Kingdom.”
Meanwhile, at home, he has been facing continued scrutiny over his own immigration policy, including how many migrants his party would take from the EU under a possible returns deal mooted last week.
Open door to 100,000 migrants
On Sunday, Pat McFadden, shadow cabinet minister, repeatedly declined to put a ceiling on the number of asylum seekers Labour would take from Europe in exchange for the ability to return those who illegally cross the Channel to England.
The Tories have claimed the potential pact would open the door to 100,000 migrants from the bloc each year.
But Sir Keir dismissed that as “complete garbage”, insisting the estimate was “nonsense” because Labour would not sign Britain up for the current EU quota scheme.
Mr McFadden, the new shadow chancellor of the Duchy of Lancaster, told Times Radio that Labour would not “accept any quotas” from Brussels but suggested “something can be done” to facilitate family reunions and help unaccompanied children.
Robert Jenrick, the Immigration Minister, claimed Labour’s policy to fix the migrant crisis was “completely falling apart”.
“He’s taking the British people for fools if he thinks they can’t see through him.”