LONDON - Brexit heated up again Wednesday, as Parliament resumed its debate of the withdrawal agreement Prime Minister Theresa May negotiated with the European Union. But British lawmakers didn't appear to be any closer to approving a deal than they were before the holidays.

"Not a single dot or comma has changed," said Jeremy Corbyn, leader of the opposition Labour Party.

May is "recklessly wasting time, holding the country to ransom with the threat of no deal in a desperate attempt to blackmail MPs to vote for her hopelessly unpopular deal," he said.

"The only way to avoid no deal," May retorted, "is to vote for the deal."

May's compromise version of what withdrawal would look like is up for a parliamentary vote Tuesday. It's a vote May postponed in December when it was clear that she would face a major defeat.

May said she has been talking with European leaders about lawmaker concerns and will give Parliament fresh assurances before Tuesday. But the EU has said it is done negotiating, and Parliament is expected to reject the deal.

May needs 320 votes to get it through. Even if every lawmaker from her Conservative Party voted with her, she would still be short four votes. And some Conservatives appear poised to defect.

Andrew Mitchell, a Conservative former chief whip, made it clear during Wednesday's debate that he won't back the current deal, calling it "the worst common denominator."

To speed up what happens next, lawmakers approved an amendment Wednesday requiring May to present Parliament with a Plan B by Jan. 21. Lawmakers would get a chance to vote on whatever she proposes, but they might also end up voting on alternatives that include a "managed no-deal Brexit" and a second referendum. The results of those additional votes wouldn't be binding, but they would show the will of Parliament.

"It's the start, I think, of an essential dialogue between government and Parliament to try and find a way out of the difficulties we are facing," Dominic Grieve, the Conservative lawmaker who tabled the amendment, told the BBC.

It's difficult to imagine, however, what sort of Brexit deal could get a majority backing.

Over the past year, Parliament has become more polarized, said Anand Menon, a professor of European politics and foreign affairs at King's College London. That makes May's job "very difficult, and it's very, very hard to see what the outcome will be."

In heated exchanges in the House of Commons, some Conservative lawmakers accused Speaker John Bercow of reflecting a bias toward anti-Brexiters in his decision to allow a vote on the amendment. One lawmaker asked Bercow about a sticker on his car that makes "derogatory comments about Brexit."

Bercow said that the car belonged to his wife, who was not the "property or chattel of her husband" and "entitled to her views." His comments drew applause from opposition lawmakers.

Those who favor Brexit as a way to reclaim British sovereignty have been reluctant to back any agreement that keeps Britain too closely tied to the EU. Many want legally binding assurances that Britain won't be permanently trapped in the Irish backstop, which would keep Britain in the EU customs union until another way is devised to avoid a hard border on the island of Ireland.

Sammy Wilson, of the Democratic Unionist Party of Northern Ireland - which props up May's minority government - tweeted Wednesday that the assurances provided by the government were "meaningless."

Brexit opponents, meantime, have yet to be convinced of a deal that offers more benefits than Britain remaining a member of the bloc.

Britain is scheduled to leave the EU on March 29, and May has repeatedly insisted that Brexit will happen then. But now there are mutterings about extending the departure date.

"We are already seeing hints on that from the government," said Tim Bale, a politics professor at Queen Mary University of London. "It strikes me we are being softened up for that possibility."

Digital Minister Margot James, who backs May's deal, said that if lawmakers do not support a Brexit deal, then the government may seek to delay Brexit. "We might have to extend Article 50," she told the BBC, adding, "But I think it's very unlikely that Parliament will actually stare down the barrel of that particular gun."

An extension also might be needed in the event of major political turmoil, such as a general election. And if Britain were to pursue a second referendum, the Constitution Unit research group at University College London estimates it could take five months to execute.

May seems to hope that the threat of Britain leaving the EU in a chaotic no-deal Brexit will push skeptics into backing her deal.

But some Brexiters have said the government warnings about the disruption caused by a no-deal Brexit - including food and medicine shortages - are exaggerated.

Boris Johnson, a former foreign secretary and prominent Brexiteer, argues that a no-deal Brexit is, actually, the "closest to what people actually voted for."