As he met with Boris Johnson at the White House, Joe Biden downplayed the chances of negotiating a post-Brexit free trade agreement with the UK.
Downing Street stated that the priority was still to reach an agreement with the United States alone.
However, according to the BBC, UK ministers are now considering joining an existing North American trade pact rather than pursuing a separate deal.
During the 90-minute meeting, the leaders of the United Kingdom and the United States also discussed Afghanistan, security, and climate change.
Speaking to reporters in the Oval Office before the meeting, Biden said the pair would discuss trade “a little bit”, adding: “We’re going to have to work that through”.
Johnson earlier downplayed the chances of securing a trade deal with the US before the next general election, saying: “The Americans do negotiate very hard.”
But after the meeting Downing Street said the two leaders “had agreed to continue working towards a future full free trade agreement”.
A deal would encourage trade by making it cheaper – usually by reducing or eliminating taxes called tariffs.
A source familiar with the government’s thinking suggested to the BBC’s Laura Kuenssberg that the UK could negotiate entry into an existing trade arrangement between the US, Canada and Mexico – known as the USMCA – set up after former US President Donald Trump tore up its predecessor, NAFTA.
“There are a variety of different ways to do this,” the source said. “The question is whether the US administration is ready. The ball is in the US’s court. It takes two to tango.”
Elsewhere, Downing Street said Johnson and Biden agreed all diplomatic and humanitarian methods must be used to stop conditions getting worse in Afghanistan.
The leaders said any international recognition of the Taliban must be contingent on the group respecting human rights.
It comes amid a request by the Taliban to address world leaders at the United Nations summit in New York this week.
Before the meeting, Biden also issued a fresh warning to the UK that peace in Northern Ireland must not be jeopardised as a result of the complications caused by Brexit – although a Downing Street source has said the issue was not raised in their private discussions.
Biden made it clear he has concerns about the Irish border, a point of tension between the White House and No 10, amid continuing issues with Northern Ireland Protocol – the arrangement which helps prevent checks along the border between Northern Ireland and the Republic of Ireland.
The meeting – taking place on the sidelines of the UN summit – also involved the traditional exchange of gifts.
Biden gave the prime minister a framed photo of their first meeting in Cornwall at the G7 summit in June, and a White House branded watch, according to officials.
Johnson gave the president a signed copy of a book written by British astronaut Tim Peake with an inscription expressing hopes that it “provides a reminder of what we’re fighting to save as our countries tackle climate change together”.
The prime minister’s gift comes weeks ahead of the COP26 climate summit, which is seen as a crucial moment to bring climate change under control.
Earlier, Biden announced the US would double its climate finance pledge and increase funding for developing countries to $US11.4 billion ($NZ16.2bn) by 2024.
Johnson said the US had “stepped up to the plate” with what he called a “massive contribution” towards the $US100bn goal for countries to raise.