Tony Blair said he believes Labour leader Jeremy Corbyn could become the next prime minister.
The ex-PM told BBC Newsnight that a year ago he would never have thought the left-wing Labour leader could win a general election, but said he now thinks it is "possible Jeremy Corbyn could become prime minister."
The two politicians have rarely seen eye to eye on issues, with Blair frequently criticising Corbyn's hard-left agenda. While Blair was the Labour prime minister between 1997 and 2007, Corbyn was a rebellious backbencher and one of his biggest critics within the party.
Before the general election, Blair urged people to vote for the Labour Party to ensure a proper opposition to Theresa May's Conservatives, but refused to endorse Corbyn.
The former prime minister admitted that he had underestimated Corbyn. "I accept now what if you'd asked me a year ago I'd have said is impossible - I accept is possible - you have to say in today's world now, there's been so many political upsets it's possible Jeremy Corbyn could become prime minister and Labour could win on that programme," Blair told Newsnight editor Ian Katz.
"For most of my political life I've been saying: 'I think this is the right way to go, and what's more it's the only way to win an election,'" he said. "I have to qualify that now. I have to say 'no - I think it's possible you end up with Jeremy Corbyn as prime minister.'"
He added that he had not changed his mind about the "wisdom" of electing a leader who at the time of the Brexit vote who delivered "frankly an unreconstructed far-left programme".
"It's a surer route to power to fight from the centre," he insisted.
Blair admitted that despite his years of political experience, he had not predicted the Brexit outcome or anticipated Trump's victory in the US presidential election. He said that while he has not changed his political beliefs, he has had to "[accept] that there's something going on in politics that [I] didn't get and don't fully understand."
Blair's interview on Newsnight will air at 10.30pm on 17 July.