Jeremy Corbyn has a spring in his step at this year’s Labour Party Conference. He’s gone from fighting for his political survival to preparing to walk into Downing Street. At least that’s what his former critics are saying.

In six months the Labour leader has gone from being outrageous outsider to prime minister-in-waiting.

Corbyn will address party delegates in Brighton this week to launch his battle for Downing Street, as tottering Tory Theresa May fends off leadership challenges from within her own cabinet.

And while Brexit goes badly, Labour has every opportunity to seize power.

“Six months ago the opposition was in a battle for survival. Now it is preparing for government,” the latest edition of the Economist crows.

Just six months ago, the exact same publication deemed Corbyn unfit to even oppose the PM in an election.

The Economist, an influential weekly magazine, said Corbyn was a “danger” who would take Britain, and Labour, “to the loony left.”

Headlines slated Corbyn, calling him an outsider who “will badly disappoint his young supporters.”

Then, a week before June’s snap election, the same publication accused Corbyn of oppression.

“No economic liberal, Mr. Corbyn does not much value personal freedom either,” the Economist said.

“An avowed human-rights campaigner, he has embraced left-wing tyrants such as Hugo Chávez and Fidel Castro (a ‘champion of social justice’), who locked up opponents and muzzled the press.

“Mr. Corbyn has spent a career claiming to stand for the oppressed while backing oppressors.”

But the tune has changed significantly.

Days ago, the Economist reported the bookies are now backing Corbyn.

“NOT even Jeremy Corbyn could quite picture himself as leader … Bookmakers have him as favorite to be Britain’s next prime minister,” it reported.

In June, Corbyn’s odds of becoming Britain’s next Prime Minister were at 9-4. Now they have been cut to 4-1 with UK bookmakers like Paddy Power.

Meanwhile, May’s address in Florence appears to have had little effect in Brussels.

It came a week after the PM saw off a challenge from her foreign secretary, Boris Johnson, who had his own vision for Brexit printed in a British newspaper.

That move alone propelled Corbyn’s crusade for Number 10, a senior source told the Telegraph.

“A lot of the party is fine with what [Boris] has done with Brexit but not if we end up with Jeremy Corbyn as Prime Minister,” the source said.

“It [The Tory government] could fall in six months.”