Now is the time for Johnson to challenge May

US President Donald Trump's former adviser Steve Bannon believes now is the time for Boris Johnson to challenge British Prime Minister Theresa May for her job, the Daily Telegraph newspaper reported yesterday.

Johnson, who led the main Brexit campaign in the 2016 referendum, resigned as foreign minister on Monday over May's strategy which he said was killing the "Brexit dream" with self-doubt.

"Theresa May has got a lot of great qualities – I am not sure if it is the right leader at the right time," Bannon, Trump's former strategist and a key player in his 2016 election campaign, was quoted by the Daily Telegraph as saying.

May's government was rattled by the departures of Johnson and her chief Brexit negotiator David Davis just days after she appeared to have gained the support of her cabinet for her strategy at a meeting at her Chequers country residence.

“Now is the moment," The Telegraph quoted him as saying. "If Boris Johnson looks at this... There comes an inflection point, the Chequers deal was an inflection point, we will have to see what happens."

Trump, in an interview with the Rupert Murdoch-owned Sun newspaper published just hours before he was due to have lunch with May, directly criticised May's Brexit strategy and heaped praise on Johnson, saying he "would be a great Prime Minister."

The US president later said he hoped for a great trade deal with Britain after Brexit.

On Friday The Telegraph said Johnson had re-joined the newspaper as a columnist with effect from Monday.