David Cameron has met with Donald Trump despite previously describing him as “divisive, stupid and wrong”.
The foreign secretary held talks with the former president as he tries to boost Republican support for Ukraine.
Trump, who will be his party’s presidential candidate in November, has previously said he could end the Russia-Ukraine war “within 24 hours”.
But experts have condemned the plan, which they say would see Kyiv forced to make major concessions to Vladimir Putin in return for an end to the conflict.
Cameron met with Trump overnight at his Mar-a-Lago estate in Florida before heading to Washington for talks with US Secretary of State Anthony Blinken.
Ahead of the meeting, a Foreign Office spokesman said: “It is standard practice for ministers to meet with opposition candidates as part of their routine international engagement.”
However, the meeting had the potential to be awkward given Cameron’s previous comments about Trump - and the former president’s well-known dislike of being criticised.
When he was still prime minister in 2016, Cameron described Trump - who was running to be president first time around - as “divisive, stupid and wrong”.
And in his memoirs after he quit Downing Street, Cameron said Trump was “protectionist, xenophobic, misogynistic”.
The foreign secretary’s talks with the former president came amid mounting concerns that Russia is gaining the upper hand in its war with Ukraine.
President Volodymyr Zelenskyy has called on the west to boost its financial support for his country - but Republicans in America have tried to block President Joe Biden’s multi-billion dollar aid package.
Cameron has previously drawn the ire of leading Republicans over his pro-Ukraine comments.
In February, leading right-winger Marjorie Taylor Greene said Cameron could “kiss my ass” after he drew comparisons between the appeasement of Adolf Hitler when urging the US Congress not to abandon Ukraine.