US President Donald Trump and first lady Melania Trump attend a welcome ceremony with Britain's Queen Elizabeth II in the garden of Buckingham Palace, in London, on the first day of a three-day state visit to Britain. Picture: Toby Melville/Pool via APBritain's Queen Elizabeth II greets President Donald Trump as he arrives for a welcome ceremony in the garden of Buckingham Palace.
Britain is scheduled to leave the EU on Oct. 31 unless both sides agree to an extension. Its position is in flux because May is stepping down as party leader Friday, setting in motion a race to succeed her as prime minister. Trump has also taken the unusual step of saying that Conservative Party leadership candidate Boris Johnson would make an "excellent" leader for the UK.