Jeremy Corbyn could win a general election, Tony Blair has admitted following months of criticism of the party leader.

Blair, who is making a partial comeback to frontline British politics, said it is “possible” Corbyn could sweep into Downing Street following two years of political upsets across the western world, including Brexit and the election of Donald Trump.

The former prime minister’s BBC interview is the latest in a series of verdicts on the Labour leadership and comes after he became embroiled in a row with Corbyn and John McDonnell over the party’s Brexit policy.

He said he still believed it is a “surer route to power” to fight an election from the centre ground but admitted his view of Labour’s prospects had changed.

“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.

“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’. 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’.”

Blair’s latest intervention will be seen as a climbdown by supporters of Corbyn and comes shortly after he used an essay on the website of the Tony Blair Institute to warn that Britain would be left “flat on its back” if Brexit was followed by “unreconstructed hard left economics”.

After Blair suggested Britain could stay in a reformed EU, McDonnell, the shadow chancellor, responded by saying the former PM “hadn’t really listened” to the debate going on around the country.