Boris Johnson has abruptly backed out of the race for 10 Downing Street, admitting he cannot unite the embattled Conservative Party.

The former prime minister said he had “reached out” to leadership rivals Risha Sunak and Penny Mordaunt to see if they could work together in the national interest, but that had not proved possible.

In a statement, he insisted he had secured the 100 nominations needed to get on the ballot – and that if he was nominated there was a “very good chance” he would be back in Downing Street by the end of the week.

He continued: “But over the last few days I have unfortunately come to the conclusion that this would simply be wrong. You cannot govern effectively unless you have a single party in parliament.

“And although I reached out to Risha and Penny – because I hoped we could come together in the national interest – we unfortunately couldn’t work out a way to do that.

“So I’m afraid the best thing is that I don’t let my candidacy go forward and support whoever succeeds.”