(Bloomberg) -- Opposition Labour leader Jeremy Corbyn gave his clearest indication yet that his party is ready to call a no-confidence ballot within days of Theresa May losing a U.K. parliamentary vote on her Brexit deal.

Lawmakers are scheduled to vote Tuesday on the agreement May reached with the European Union, and the prime minister appears no closer to getting the backing she needs than she was in December, when the vote was dramatically pulled after it became clear the government was heading for a heavy defeat.

Speaking on BBC’s “Andrew Marr Show” Sunday, Corbyn said a confidence vote would be brought “at a time of our choosing,” but “it is going to be soon, don’t worry about that.”

His warning came as May made a last-ditch appeal to members of Parliament, saying opponents of her deal risk letting down those who voted to leave the EU in the 2016 referendum.

“Doing so would be a catastrophic and unforgivable breach of trust in our democracy,” she wrote in the Sunday Express newspaper.

Pound, Homes

A defeat would leave Britain on course to crash out of the 28-nation EU on March 29 with no new trading arrangements in place. According to Bank of England analysis, such a chaotic split could hammer the pound and house prices and plunge Britain into a recession worse than the financial crisis a decade ago.

Corbyn is seeking to topple government by forcing a general election. Under British electoral law, May’s Conservatives would have two weeks following the loss of a confidence vote to try to form a new government. If they fail, an election will be called.

The Labour leader faces a major hurdle: his chances of winning a confidence vote are slim, as he’d have to gain the support of both Tory and Northern Irish lawmakers, who fear a Labour takeover of government. If a confidence vote failed, he’d be under pressure to back a second Brexit referendum, risking a backlash from the many Labour supporters who voted to leave the EU.

Corbyn said he’d prefer to see a negotiated deal than a second referendum. A no-deal Brexit would be “catastrophic” for industry and trade, he said. Labour says it wants a full, permanent customs union with the EU.

‘Everything We Can’

“We will do everything we can to prevent a no-deal exit,” Corbyn said on the BBC.

The Sunday Times reported that some lawmakers are planning to seize control of the legislative agenda from the government in an act that would allow Parliament to extend the Brexit deadline or even overturn the decision to leave the EU.

In a warning to Conservative rebels ahead of the vote, Brexit Secretary Stephen Barclay warned that Brexiteers seeking “ideological purity” are in danger of seeing Britain not leave the EU at all. But asked about a Brexit Plan B, Barclay hinted that May is not ready to ditch her plan if it’s defeated, saying he “strongly suspects” lawmakers will end up voting for “something along the lines” of the current deal.

Meanwhile, the EU is waiting to see the outcome of Tuesday’s vote -- and the size of the defeat -- before considering its response, officials said, with some predicting that she will have to delay Brexit.

A margin of defeat exceeding about 60 lawmakers would probably mean the agreement is close to death and negotiations are in uncharted waters, several EU officials said. A narrower defeat and the bloc may look at fresh ways of making the agreement more palatable to get it across the line in Parliament.

The EU is expected to publish a letter on Monday in which the bloc will reiterate that the controversial Irish backstop arrangement, if it is triggered, will only be temporary. But the contents are unlikely to assuage the concerns of Brexiteers who fear Britain will end up being tied to EU trade rules indefinitely.

--With assistance from Ian Wishart.

To contact the reporter on this story: Andrew Atkinson in London at a.atkinson@bloomberg.net

To contact the editors responsible for this story: Fergal O'Brien at fobrien@bloomberg.net, Steve Geimann

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