New Jersey’s Governor and Republican presidential hopeful Chris Christie is to begin his three-day visit to the UK.
Mr Christie will hold a series of meetings with top British politicians, including Prime Minister David Cameron.
Officially, his trip is a trade mission to promote ties with New Jersey’s third largest foreign partner, with $7bn (£4.6bn) in goods exchanged in 2014.
But it is also seen as a chance to boost his foreign policy credentials ahead of the 2016 White House race.
Although the elections are still more than 18 months away, rival Republican contenders are currently trying to ensure they have enough donors to fund their campaigns, the BBC’s Naomi Grimley in Washington reports.