Joe Biden has said he is not currently planning to run against Donald Trump in the 2020 presidential election, but appeared to leave the door open to seeking the Democratic nomination.

Speaking in London, the former vice-president said he was not an “aspiring candidate” for his party “at this point”.

During a passionate address at Chatham House on Wednesday afternoon, the former senator repeatedly underscored the importance of the US relations with Europe, in comments that amounted to a clear challenge to Mr Trump’s policies.

“Looking inward, turning inward, has never, ever worked for us before,” he said, adding the ”special relationship” between the US and UK still formed the “core” of transatlantic alliances.

Mr Biden sidestepped a question about his intentions for 2020, saying there were "many" potential contenders capable of beating Mr Trump.

He added "Not single aspiring candidate that I can think of for the nomination - and I am not one at this point - does not have a better understanding and formulation of American foreign policy than President Trump."

Barack Obama’s former deputy has previously said he would decide by January whether to run in the presidential election. He has pointed to preliminary polling data which suggested he could defeat Mr Trump.

In July, Mr Biden said he would hold what he called an “altar call” – a chance for Democrats to voice their commitment to endorse his bid – after the November 2018 midterms.

Speaking at Chatham House, he predicted his party would win control both the House of Representatives and the Senate in next month’s elections, which he described as “a battle for the soul of America”.

“I predict to you that the Democrats will win 40 seats in the House. I also think there is a better than even chance we win the Senate,” he said.

Mr Biden revealed that he met prime minister Theresa May on Tuesday, and described Brexit as "an almost intractable problem" that threatened US influence on the world stage.

"I do believe very strongly that the United States's ability to play a major role in the security of the west and the prosperity of the transatlantic partnership rests in part on Great Britain's influence in Europe," he said.

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Mr Biden toyed with the idea of running for the White House in 2016, but he ruled it out as he was still mourning the death of his 46-year-old son Beau, who had a rare form of brain cancer.

He previously vied to be the Democrats' nominee in 1988 and 2008.

The former vice-president will be 77 on election day in 2020, something which is a concern among Democrats.

However, he is one of party’s leading figures on foreign policy and is seen as having greater national appeal than many younger potential candidates.

Others said to be considering a run are New York governor Andrew Cuomo, and senators Cory Booker, Kamala Harris, and Kirsten Gillibrand.