There is talk in Westminster of Theresa May calling an imminent election to break the Brexit deadlock.

That might seem highly unwise, to put it mildly. Last time May did that in 2017 (after promising not to) her party was punished by voters and lost its majority in parliament. With U.K. politics now in deep crisis over a Brexit deal that May herself negotiated, would she really offer voters the chance to deliver the coup de grâce?

Downing Street denies an election is coming but the prime minister may find herself with little choice: Call an election now or have one thrust upon her later.

MPs who have war-gamed the next few phases of the Brexit drama believe the government is now penned in, unable to move in any direction without stumbling over a trip-wire that triggers a general election.

“Whatever happens, at some point we’re looking at the government losing a vote of confidence,” one senior Tory MP said.

Their reasoning? The first thing to note is that, barring a dramatic change in Brussels’ stance, there can be no Brexit deal without the Northern Irish backstop in it.

Second, May’s confidence-and-supply partners the Democratic Unionist Party are unshakeably opposed to the backstop. Leader Arlene Foster said in November that if May’s deal were to pass, her party would “revisit” the confidence-and-supply agreement that keeps the government afloat.

A party spokesman confirmed to POLITICO that this remains the case. If the backstop is “foisted on us then that would be a breach of the confidence-and-supply agreement” because, “central to that agreement was a commitment to strengthening the Union.”

The DUP’s 10 MPs were the difference between May winning this week’s confidence vote and losing it. While the party does not explicitly say they would vote against the government if a Brexit deal with a backstop passes and Labour subsequently tries another vote of confidence, that is the clear implication of their position.

Even if the DUP didn’t take the plunge of opposing the government in a vote of no confidence, without their support the Conservatives would find it impossible to govern so may need a general election anyway.

Either the Brexit deal falls, or her majority does.

The stance of Brexiteer Tories in such a situation is uncertain. Jacob Rees-Mogg, who leads the backbench Brexiteer caucus, has said he will never oppose May in a confidence vote. Others may take a different view.

Either way, there is a very real possibility that a Brexit deal (with the backstop) securing a parliamentary majority will paradoxically spell the end of May’s governing majority.

Either the Brexit deal falls, or her majority does. They cannot co-exist.

This comes with the caveat that the DUP might be bluffing. But this is a party that places the union of the United Kingdom above all else. It is possible they would accept the risk of Labour winning any election that followed, believing that a softer Brexit that negates the need for the backstop might be the outcome. DUP "sources" told the Times today that the party is prepared to countenance a softer Brexit, so long as there is no threat to the union — although Arlene Foster insisted the story is “inaccurate.”

There would also be the option, in the 14 days between a successful no-confidence vote and an election being called, that the DUP could offer their support to any new Tory leader who pledged to take the U.K. out of the EU without a deal. That’s another way to kill the backstop.

But in that scenario, a would-be Brexiteer Tory leader would struggle to put together a majority because pro-EU Conservatives would not countenance a no-deal exit.

Which brings us to the other trip-wire currently lying in May’s path.

If she has calculated all of the above, and chooses instead to go for no-deal in order to avoid losing the DUP, then she may lose Tory MPs who want to call off Brexit or leave with a softer Norway-style deal. In the confidence vote that Labour would inevitably call in such a scenario those Tories may vote against their own government.

Backbencher Nick Boles has already suggested he would do as much and others would likely follow. If enough did, the result: the collapse of the government and, most likely, a general election.

So deal or no deal, an election seems increasingly probable. Despite her protestations to the contrary, the prime minister may decide it is better to call one on her own terms.

This insight is from POLITICO’s Brexit Files newsletter, a daily afternoon digest of the best coverage and analysis of Britain’s decision to leave the EU. Read today’s edition or subscribe here.