After two years of fraught negotiations and a dozen ministerial resignations, Prime Minister Theresa May secured the European Union’s blessing on Sunday for a Brexit deal that would allow Britain to withdraw from the bloc with minimal economic damage. And yet, with only months remaining until the March 29 deadline, Parliament appears poised to reject the agreement, potentially setting Britain on course to crash out of the E.U. with no deal, no formal trade relationship, and an avalanche of new customs duties that would turn the United Kingdom into a geopolitical backwater.

The deal, such as it is, reflects a tepid bureaucratic compromise. For nearly two years, Britain would be left outside the E.U. but still subject to E.U. laws and regulations, effectively preserving the status quo until the two parties can hammer out the Gordian details of their new arrangement. Should they fail to do so before the transition period ends in 2020, a number of legal backstops would kick in, on terms largely favorable to Brussels. Either way, Britain would be obliged to pay the £39 billion divorce bill and likely give up Gibraltar, its territorial stepchild abutting Spain.

Although May campaigned against the Brexit referendum, herself, the prime minister has since adopted a certain world-weary resolve to see her task through to its grim conclusion. “It’s the only possible deal,” May said Sunday, shortly after the EU27 leaders signed off, urging Parliament to see reason. Brussels, too, has made clear that no other offer will be forthcoming. “This is the deal,” said president of the European Commission Jean-Claude Juncker Sunday, “It’s the best deal possible. The European Union will not change its fundamental position.” Britain can take it or leave it.

Parliament, it seems, will take their chances. While May and her whips prepare a two-week P.R. blitz to sell the deal, an unlikely coalition of Remainers and Brexiteers have already assembled against it, united in their belief that the May-Juncker deal will leave the U.K. stranded in a no-man’s-land between independence and membership. Euroskeptics are particularly hostile toward the “backstop” arrangement at the Irish border, which would keep the U.K. in the customs union while Northern Ireland follows single market rules, should future trade negotiations fail. The Democratic Unionist Party, which props up May’s ruling Conservative government, have already expressed their opposition, as have the Liberal Democrats, the Scottish National Party, and Jeremy Corbyn’s Labour Party (most of it, anyway). About 80 Tory M.P.s have signaled their opposition, divided between those seeking a more aggressive separation from Europe and a minority who want to abandon Brexit entirely. Further complicating matters is Donald Trump, who warned Monday that the U.K.-E.U. deal would limit Britain’s ability to trade with the U.S.

May defended the deal against Trump on Tuesday, insisting that the U.K. “will be able to do trade deals with countries around the rest of the world.” If she wins the Withdrawal Agreement vote, currently scheduled for December 11, British and E.U. negotiators would begin a 21-month transition period in which all such quirks—Northern Ireland’s border, trade deals, fishing rights, intelligence sharing—would presumably be ironed out. And yet, it is difficult to see how either May or her government survive the current political crisis. The Withdrawal Vote will almost certainly fail—May’s parliamentary whip has reportedly said as much—possibly ending May’s run as prime minister, too.

What comes next is even less clear. There could feasibly be a second referendum, or a general election. But given the likely market reaction, both these options seem less agreeable than May being forced back to the drawing board. E.U. partners, who want to make leaving the bloc as unappealing as possible, would be aggravated, at the very least. Perhaps Brussels would reopen discussions, but it is hard to imagine renegotiations would yield a substantially different deal. With the countdown clock still ticking, Parliament would then be left in much the same place as it is right now: contemplating a lose-lose Brexit deal that hardly anybody wants.

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