UK Prime Minister Theresa May has announced her departure from politics after pressure on her reached a critical point following her Brexit failures.

US President Donald Trump says Boris Johnson would be an “excellent” choice to replace British Prime Minister Theresa May, days ahead of a state visit to London.

“I actually have studied it very hard. I know the different players,” he said in an interview with The Sun.

“But I think Boris would do a very good job. I think he would be excellent.”

“I like him. I have always liked him. I don’t know that he is going to be chosen, but I think he is a very good guy, a very talented person.”

The US president also said other candidates in the race to replace Mrs May, who will step down as leader of the Conservative party on June 7 after failing to push her Brexit deal through parliament, had also sought his endorsement.

“I don’t want to say who but other people have asked me for endorsements, yes,” he said.

“I could help anybody if I endorse them. I mean, we’ve had endorsements where they have gone up for forty, fifty points at a shot,” Trump claimed.

Labour leader Jeremy Corbyn criticised Trump’s remarks.

“President Trump’s attempt to decide who will be Britain’s next prime minister is an entirely unacceptable interference in our country’s democracy,” Corbyn said in a statement.

“The next prime minister should be chosen not by the US president, nor by 100,000 unrepresentative Conservative Party members, but by the British people in a general election,” Corbyn added.

The US president also criticised Mrs May for playing a weak hand in her Brexit negotiations, saying: “I think that the UK allowed the European Union to have all the cards. And it is very hard to play well when one side has all the advantage.

“I had mentioned to Theresa that you have got to build up your ammunition.”

The US president gave a similarly controversial interview before his first official visit to Britain last year, when he said May had ignored his advice on Brexit negotiations and also said Mr Johnson would make a “great prime minister”.