The US president revealed the two leaders had a “good” phone call about the “outstanding” US-UK relationship – a stark contrast to Trump’s harsh criticism of Burnham’s predecessor, Keir Starmer.

Andy Burnham faces a daunting in-tray as Britain’s new prime minister, from a slowing economy and strained services to volatile global crises and US ties.

The stage is set for the 7th Prime Minister in 10 years as Andy Burnham prepares for Downing Street.

The United Kingdom's new Prime Minister Andy Burnham delivers a speech outside 10 Downing Street in London after taking office on Monday. [Isabel Infantes / REUTERS]

Andy Burnham promises unity and tangible improvements as he steps into the UK premiership amid pressing challenges and cabinet uncertainties.