Watch as David Cameron holds a joint press conference with US secretary of state Antony Blinken in Washington DC on Tuesday 9 April.
The foreign secretary has already held talks with Donald Trump in Florida amid his push to shore up US support for Ukraine.
Lord Cameron met with the presumptive Republican presidential candidate on Monday ahead of his trip to DC to appeal to Congress over a stalled package of aid.
On his visit to the US capital, he will warn that success for Kyiv in defeating Russia is “vital for American and European security” as he urges lawmakers across the Atlantic to approve “urgent” further assistance for the country.
Lord Cameron will push for Ukraine to be given the resources needed to “hold the line” and “go on the offensive” in 2025, the Foreign Office said.
He will meet with Mr Blinken as well as Congressional leaders, who he will urge to “change the narrative” on support for Ukraine while a multibillion-dollar aid package remains held up on Capitol Hill.