US President Donald Trump has said he could “work with anybody” in No 10 – nine days ahead of a general election.
Speaking on a three-day visit to the UK, Mr Trump said he would “stay out of the election”, that he was a “fan of Brexit” and that he thought PM Boris Johnson was “very capable”.
Mr Trump is in the UK for a Nato summit being held in Watford on Wednesday.
He will attend a reception hosted by the Queen later at Buckingham Palace later, where protests are expected.
Scotland Yard has said road closures will be in place in central London during the Nato summit.
President Trump is due to have separate talks with German Chancellor Angela Merkel, French President Emmanuel Macron and Nato Secretary General Jens Stoltenberg.
And he will attend a working lunch with representatives from Estonia, Greece, Latvia, Poland, Romania, Lithuania, Bulgaria and the UK.
It is unclear whether there will be a one-on-one meeting between UK Prime Minister Boris Johnson and Mr Trump.
BBC diplomatic correspondent James Lansdale said the Conservatives’ HQ wanted to avoid such a meeting “to avoid pictures that could be used by his (Boris Johnson’s) opponents” in the upcoming general election.
Foreign Secretary Dominic Raab – who will meet US Secretary of State Mike Pompeo later – said arrangements for such bilateral meetings were “always quite fluid”.
He told BBC Radio 4’s Today programme: “The role of this leaders’ summit – and we’re hosting it – is for the prime minister to bring all of our north American and European partners together and show, through Nato, we can be bigger than the sum of our parts.”
Mr Johnson and Mr Trump did speak on Saturday, when Mr Trump expressed his condolences after the London Bridge attack.
In a recent radio interview, Mr Johnson warned the US president against getting involved in the general election on 12 December. He has previously been criticised for voicing his opinions of British political leaders.
Mr Trump later said he was “absolutely cognisant” of the importance of not interfering in other countries’ elections.
Labour leader Jeremy Corbyn has called for Mr Trump to be treated with “with respect and politeness” during his visit.
Mr Corbyn has written to Mr Trump, demanding assurances that the NHS will be “off the table” in any post-Brexit US-UK trade talks. However, Mr Johnson said the claims were “nonsense” and the NHS would not be part of any such trade discussions.
Meanwhile, Mr Johnson has told the Sun newspaper that Mr Corbyn wants to “disband” Nato and accused the Labour leader of being “naive” to the risk of terrorism.
In response, a Labour spokesman said that Mr Corbyn “will do whatever is necessary and effective to keep the British people safe”.
Leaders including Mr Trump and Mr Corbyn will gather for a reception at Buckingham Palace later.
Protesters are expected to gather outside the palace ahead of the event on Tuesday evening.
The family of Harry Dunn – the teenage motorcyclist, whose death has led to a diplomatic row with the US – will be among those demonstrating, a family spokesman has said.
Mr Dunn died after a collision with a car driven by a US diplomat’s wife, who has since left the UK claiming diplomatic immunity.
Radd Seiger said Mr Dunn’s parents and friends will “make our feelings known” to Mr Trump.