Brexit Vote: With Just Hours to Go, Parliament Debates E.U. Withdrawal Plan

After two and a half years of negotiation, argument, predictions and posturing, Parliament will finally decide on Tuesday on a bill dictating the terms of Britain’s departure from the European Union, one of the most important votes lawmakers are likely to cast in their careers.

• Prime Minister Theresa May has struggled to convince Parliament — and Britain — that the divorce deal she negotiated with Brussels is the best way forward. But she hasn’t made the sale. The House of Commons is expected to defeat the deal by a wide margin, and no one is certain what will come next.

• Much is at stake: Britain’s place in Europe, its economic future and possibly the survival of Mrs. May’s Conservative government.

• Debate should end late this afternoon, with voting scheduled to start at 7 p.m. in London (2 p.m. Eastern). Four amendments to the agreement will be considered before there is a vote on the bill itself.

A marathon debate begins its final lap

At long last, the final day of debate began, with Geoffrey Cox, the attorney general, making the government’s case.

Ordinarily, a legislator in that position would face the opposition benches, but Mr. Cox repeatedly turned to address critics on the Conservative side, an indication of how steep an uphill battle the government faces.

“Do we opt for order, or do we choose chaos?” he demanded. “What are you playing at? You are not children in the playground.”

Mr. Cox, an esteemed trial lawyer, has a booming voice and formidable rhetorical skill, but he chose an image he may regret. The agreement, he said, is like an airlock linking two space capsules — a brief stop on the way to an as-yet-unknown long-term pact with the European Union.

Within minutes, opponents seized on the metaphor.

“On the other side of the airlock is a complete vacuum,” said Hilary Benn, a Labour member and chairman of the house’s Brexit committee.

Dominic Grieve, a Conservative lawmaker, said, “We will either choke to death as a nation in the airlock or, when the door finally opens, we will find the landscape little to our liking.” — Richard Pérez-Peña

Long-awaited bill faces dim prospects

Since June 2016, when 52 percent of British voters approved a referendum to leave the European Union, everything has built up to the vote on Tuesday. The bill would determine the trade and immigration relationship between Britain and the bloc through the end of 2020, while a permanent agreement is negotiated.

Long before lawmakers began debating Prime Minister Theresa May’s bill in December, it seemed doomed.

She postponed the vote for a month, rather than face a humiliating defeat, as she tried to win new promises from Brussels. But the parliamentary calculus has not changed.

Mrs. May’s Conservative Party is divided over the plan — one of her whips stepped down on Monday so that he could vote against it, the latest in a long string of Brexit-related resignations — and the opposition parties overwhelmingly oppose it. — Richard Pérez-Peña

What happens next?

With Prime Minister Theresa May’s bill expected to lose, the question dominating British politics is: What comes next?

If the agreement is not approved, she would have until Monday to present a backup plan to Parliament. The range of possibilities is wide, unappealing and a bit bewildering.

If the deal loses by a narrow margin, she might be able to win a few concessions from Brussels and return to Parliament for a second vote. But if the defeat is a crushing one, that option is likely to be unavailable.

As things now stand, Britain will leave the European Union on March 29. Neither Mrs. May’s government nor the European bloc wants that to happen without an agreement in place — most experts predict that a no-deal Brexit would be chaotic and economically damaging.

With little time left to negotiate anew, the prime minister may be forced to ask Parliament to postpone Brexit.

She could also call a second referendum, an option favored by lawmakers who hope that British voters have changed their minds.

The Labour Party leader, Jeremy Corbyn, wants to force early elections, and seems likely to call for a vote of no confidence in the government.

But a note of caution about those who would write off Mrs. May when the situation looks bleak. She has been here before. And before that. And, yes, before that, too. — Richard Pérez-Peña

For businesses, a chance to gain clarity

The vote will provide little of the detail that businesses need to plan their operations, but it could at least narrow the options.

“The longer this Brexit political drama continues, the less and less attractive the U.K. is going to be” to investors, Iain Anderson, the executive chairman of the consulting firm Cicero Group, said last week.

Although many businesses are preparing for the worst-case scenario — crashing out of the European Union without a deal in place — they have also been vocal in warning against it.

“Make no mistake, no-deal cannot be ‘managed,’ ” Carolyn Fairbairn, the director general of the Confederation of British Industry, said last week.

The government has tried, mostly unsuccessfully, to ease public anxiety over a no-deal scenario. Last week it created an artificial traffic jam to test how to manage disruption at the border, an exercise that was widely derided.

Manufacturers fear that a no-deal exit would wreak havoc on just-in-time manufacturing, which relies on parts crossing borders and arriving within minutes of assembly. — Amie Tsang

The deal is taking fire from multiple directions

There are many objections to the Brexit bill, making clear that no approach to leaving the European Union commands anything close to majority support.

Hard-line pro-Brexit Conservatives argue that the deal ties Britain much too closely to European trade rules for the foreseeable future. Many contend that a no-deal exit from the bloc would be preferable.

The 1998 accord that brought peace to Northern Ireland guarantees free movement of goods and people between that part of Britain and the Republic of Ireland, a European Union member. But many Conservatives, and the Democratic Unionist Party, a small group in Northern Ireland allied with Prime Minister Theresa May’s government, object to the way the proposal would protect that guarantee.

The deal Mrs. May reached with Brussels includes a “backstop” that would keep Northern Ireland more closely tied to the bloc than with the rest of Britain if the two sides are unable to reach a long-term agreement by the end of 2020. Critics say that would effectively divide Britain in two.

There are lawmakers in several parties who oppose Brexit in any form and want a second referendum. And Mrs. May has accused the opposition Labour Party of political opportunism, by simply opposing anything her government tries to do. — Richard Pérez-Peña

Parliament speaker is caught in the middle

He’s the unlikeliest star of this season of Brexit, alternately reviled and adored and often on tabloid front pages: John Bercow, the House of Commons speaker. His job, as the highest authority in the chamber, is to preside over debates and, mostly, to get members to shut up.

The role is supposed to be strictly nonpartisan.

But Mr. Bercow — easily recognizable with his floppy silver hair and booming voice — now finds himself in the position of an umpire who makes a controversial call in the early innings that could tip the whole game.

Last week, a member of Parliament proposed requiring Prime Minister Theresa May to return within three days to announce what the government would do next if the original deal was rejected. She previously had 21 days to decide.

That decision tipped the balance of power to Parliament from Mrs. May’s government, and will let lawmakers weigh in with alternatives.

And Mr. Bercow may not be done yet. Commentators said it could end up being the most radical shift in relations between the government and Parliament since the speaker defied King Charles I in 1642. — Benjamin Mueller