LONDON - Like white smoke from the Vatican announcing a new pope, the signal from Britain's Cabinet table said: We have a decision.
After a year and a half of negotiating with the European Union -- and fighting with itself -- the U.K. government on Wednesday backed a deal to allow Britain's orderly exit from the bloc and paint the outlines of future relations.
In a hard-won victory, British Prime Minister Theresa May on Wednesday persuaded her Cabinet to back a draft divorce agreement with the European Union, a decision that triggers the final steps on the long and rocky road to Brexit.
May's fractious Conservative government agreed on a deal that solves the key outstanding issue -- how to ensure a frictionless border between the U.K.'s Northern Ireland and EU member Ireland after Brexit. The "backstop" plan involves keeping the U.K. in a customs union with the EU until a permanent trade treaty is worked out.
It's a breakthrough, but the path to Brexit day -- just over four months away on March 29 -- remains rocky. May still faces pitfalls and threats from her domestic opponents as she tries to navigate the U.K.'s orderly exit from the EU.
The prime minister hailed the Cabinet decision as a "decisive step" toward finalizing the exit deal with the EU within days. It sets in motion an elaborate diplomatic choreography of statements and meetings.
Many in the divided Conservative Party believe May's proposal leaves Europe with too much control over Britain's trade and borders, certainly if the U.K. remains for any considerable period part of the bloc's customs union. More philosophically, and perhaps more important from a public perspective, they argue that such a deal would betray the British public's will after the majority vote to leave the EU.
May insists her proposal delivers on key promises to reduce Europe's checks on British trade and immigration. "We will deliver Brexit. We will not rerun the referendum," she vowed on the floor of the British Parliament on Wednesday.
"I firmly believe, with my head and my heart, that this is a decision which is in the best interests of the United Kingdom," she said. And in a warning to her opponents, May added that the choice was between her deal, "or leave with no deal; or no Brexit at all."
The draft divorce agreement between Britain and the European Union has two parts: a legally binding withdrawal agreement, which runs more than 580 pages, and a looser political declaration on future relations.
Here are some key points in the deal May got her government to agree to:
Transition period: Britain will leave the EU on March 29 but remain inside the bloc's single market and be bound by its rules until the end of December 2020, while the two sides work out a new trade relationship. The transition period can be extended by joint agreement before July 1, 2020 if both parties decide more time is needed.
Irish border: The deal commits the two sides to a "backstop" solution to guarantee the border between EU member Ireland and the U.K.'s Northern Ireland remains free of customs posts or other obstacles. It keeps the U.K. in a customs arrangement with the EU, and it will last until superseded by permanent new trade arrangements. Both sides said they hope to have a new deal in place by the end of 2020, so the backstop is never needed.
Divorce bill: Britain agrees to cover contributions to staff pensions and commitments to EU programs the U.K. made while a member for the funding period that runs to 2020. The bill has previously been estimated at about 39 billion pounds ($50 billion).
Citizens' rights: EU citizens living in Britain, and Britons elsewhere in the bloc, will continue to have the rights to live and work that they have now.
The seven-page political declaration says Britain and the EU will seek a "free trade area combining deep regulatory and customs cooperation," and "ambitious, comprehensive and balanced" arrangements for the services sector.
Other ambitions include visa-free travel for short-term visits, smooth railroad, air and sea transport, and "comprehensive, close, balanced and reciprocal law enforcement and judicial cooperation."
Details will be worked out after the U.K. leaves the EU on March 29.
Here's a look at what's likely to happen next:
Beeline to Brussels
May is due to update Parliament on Thursday on what has been agreed, while Brexit Secretary Dominic Raab will likely head to Brussels to meet with chief EU negotiator Michel Barnier.
Barnier declared there has been "decisive progress" toward a deal -- the phrase that allows EU leaders to call a special summit to approve the deal. They have penciled in a meeting for Nov. 25.
Peril in Parliament
Once the EU has signed off on it, the deal also must be approved by the European and British parliaments
May hopes to get it passed by U.K. lawmakers before Christmas. Business groups warn that most U.K. companies will implement Brexit contingency plans -- cutting jobs, stockpiling goods, relocating production -- if there isn't clarity by then about the terms of Brexit.
But she faces an uphill battle. May's Conservative Party doesn't hold a majority of seats in the House of Commons and relies on 10 lawmakers from Northern Ireland's Democratic Unionist Party to win votes. But the DUP said it will reject any deal that treats Northern Ireland differently to the rest of the U.K.
Several dozen pro-Brexit Conservatives have vowed to oppose any arrangement that keeps Britain in a customs union and tied to EU trade rules, indefinitely.
The main opposition Labour Party also said it will oppose any deal that doesn't offer the same benefits Britain currently has as a member of the EU's single market and customs union.
May is calculating that, faced with the prospect of a chaotic "no-deal" exit -- complete with financial turmoil, gridlock at U.K. ports and shortages of essential goods -- most Conservatives and some opposition lawmakers will crumble and support the deal.
Possibility of a party rebellion
If enough senior members of May's party balk at the deal, it could still lead to a challenge for the leadership of the party. In Britain's version of democracy, that means she could theoretically be unseated as Prime Minister and her entire government replaced through a snap election.
A senior party member warned hardline Conservative "Brexiteers" on Wednesday, that if they fail to back May's proposal, it could backfire on them.
Former Conservative Party leader William Hague, who voted to "Remain" in the 2016 referendum, said the public's decision must now be respected, and warned that rejecting May's proposal in hopes of a better deal would be inherently risky: "If you don't take this opportunity to leave the EU, to get Brexit over the line, you might never leave at all," he told BBC's Radio 4.
If Parliament rejects the deal, Britain enters unknown territory.
Lawmakers could try to send the government back to the negotiating table with the EU, though there's no simple mechanism to make that happen. They could defeat the government in a no-confidence vote in an attempt to trigger a national election.
They could even vote for a new referendum on EU membership, though it seems unlikely there would be time to hold one before the U.K.'s scheduled departure date. The U.K. will cease to be an EU member on March 29 -- deal or no deal.
Iain Begg, a professor at the London School of Economics' European Institute, said rejection of a deal would trigger a major political crisis because Britain's patchwork constitution offers no "prescribed way out of that dilemma."
He said in that case, "we really are into a period of great uncertainty about what happens next. I think nobody can know how it would unfold."