LIVERPOOL, England (Reuters) - British opposition leader Jeremy Corbyn said on Wednesday Labour would vote against a Brexit deal based on Theresa May’s proposals, the strongest warning yet to a prime minister whose plan to leave the European Union is hanging by a thread.

On the final day of his party’s annual conference, Corbyn sought to show he was ready to take up the reins of power, setting out details of what he called “a radical plan to rebuild” Britain, including the promise of a “green jobs revolution”.

Corbyn also made a direct bid for the support of those outside the British capital who voted to exit the EU, often in frustration at feeling left behind by a London-based elite, saying Labour was ready to take over the tortured Brexit talks.

Britain is not due another election until 2022, but Labour is preparing for a possible snap vote. May’s position, already precarious, was further weakened last week when the EU rebuffed her Brexit proposal, known as “Chequers”, which is also unpopular in her Conservative Party.

Corbyn, a veteran eurosceptic, said Labour respected the outcome of a 2016 referendum when Britons voted to leave the EU, in the biggest shift in foreign and trade policy in more than 40 years.

“As it stands, Labour will vote against the Chequers plan or whatever is left of it and oppose leaving the EU with no deal,” Corbyn told a packed hall at the conference in the northern English city of Liverpool.

“And it is inconceivable that we should crash out of Europe with no deal - that would be a national disaster. That is why if parliament votes down a Tory (Conservative) deal or the government fails to reach any deal at all we would press for a general election,” he said to a standing ovation.

Brexit divides Labour just as it does May’s Conservatives and much of the country, but Corbyn has tried to paper over his party’s splits by keeping open the option of holding a second referendum on staying in the EU.

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REVOLUTION?

His words were greeted with chants of “Oh Jeremy Corbyn”, a popular refrain since 2015 when he became leader of Labour, a party which seems to be growing in confidence after months of rows over anti-Semitism and other issues.

Corbyn has presided over a marked move leftwards in policy, breaking with what he described as the “greed-is-good, deregulated financial capitalism” that led to the 2008 financial crisis. He accused politicians, including in Labour, of failing to make “essential changes to a broken economic system”.

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“That’s why Labour is offering a radical plan to rebuild and transform Britain,” he said.

Corbyn pledged to create more than 400,000 skilled jobs by investing in technologies to cut net carbon emissions by 60 percent by 2030, and to zero by 2050 - a move the Conservatives criticized as Labour’s “37th unfunded promise”.

But pro-EU Labour lawmakers said it is on Brexit where he could falter.

For now, Corbyn seemed to bridge the gap between those in Labour who want a clean break with the EU and others, especially in the parliamentary party, who want the closest possible ties with the bloc, or even to stop Brexit altogether.

By saying he will vote against Chequers, he has thrown down the gauntlet to May, who has promised to press on with her plan to leave the EU, named after her country residence where an agreement was hashed out with her ministers in July.

With a working majority of only 13 in the 650-seat parliament and a former junior minister warning that as many as 80 of her own lawmakers could vote against it, May could have been hoping to secure some support from the opposition.

But Corbyn told May that Labour would only back a “sensible deal”. If she cannot secure one, she should “make way for a party that can”, Corbyn added, before leaving the stage to strains of “Children of the revolution” by rock group T-Rex.