Donald Trump has indicated Boris Johnson is his preferred Conservative leadership candidate amid growing White House frustration over Brexit.

The US President stopped short of formally endorsing the former foreign secretary on Thursday but described him as a "friend" for whom he had “a lot of respect”.

He is expected to hold private talks with Mr Johnson during next week's state visit in what would be a notable breach of convention.

Nigel Farage, the Brexit Party leader who campaigned for the US president in 2016, may also be invited, sparking speculation the President may seek to act as a go-between to encourage the two men to form a political alliance.

Senior US administration figures have talked up a Boris-Farage pact, likening it to Ronald Reagan's blue collar conservatism that won the Republicans 12 years in the White House.