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If Boris Johnson can manage to produce a Brexit deal in the next fortnight, can he get Parliament to vote for it? From the U.K. prime minister’s point of view, the lack of noise is probably a good thing.

Theresa May’s negotiations with the European Union were conducted against a soundtrack of angry warnings from members of Parliament in her Conservative Party. She’d better not sell them out, they said, and even before she had a deal, many of them were committed to voting against it -- Johnson included.

But on Friday there were no warning shots fired on the news channels, no delegations walking up Downing Street to lay down the law with the prime minister. For the toughest Conservative Brexiteers, the calculation has changed.

There are 28 Conservative MPs who have so far refused to vote for any Brexit deal. In March, when others, including Johnson and Jacob Rees-Mogg, gave way and backed May’s agreement, they refused to give in. They named themselves the “Spartans,” after the Greek warriors who fought the Persian army at the Battle of Thermopylae in 480 BC.

Until a month ago, the Spartans were content to promise to vote against any Brexit deal they didn’t like, believing the alternative would be to leave the EU without any deal at all on Oct. 31 -- an outcome some of them actively want. The passage of a law intended to stop a no-deal Brexit -- known as the Benn Act -- has made them wonder whether that’s still realistic.

Extension Threat

Instead of leaving the EU this month, they fear the U.K. will be forced to seek a further extension to talks. That could see them fighting an election where Nigel Farage’s Brexit Party splits the Conservative vote and them losing power altogether, leading to another Brexit referendum.

Bluntly, the question for the Spartans is whether a Brexit they don’t like is better than no Brexit at all.

The same question applies to Northern Ireland’s Democratic Unionist Party, who along with the Spartans refused to back May. They too were staying quiet. Johnson had spoken to DUP leader Arlene Foster and his office was keeping the party informed.

Foster issued a noncommittal statement Friday afternoon, though made clear the party hadn’t made up its mind. If Johnson can keep them on board, the support of most of the Spartans will be secure.

Invisible Border

The DUP’s choice is complicated because a no-deal Brexit would harm their voters, many of whom have got used to doing business across Ireland’s invisible border. Though the party has opposed anything that might create a boundary in the Irish Sea between Northern Ireland and the rest of the U.K., they were ready to bend that principle when Johnson asked them at the start of the month.

But even if the DUP ultimately denounces the deal, the Spartan wobble could mean they find themselves lonelier than they were in March. That too could affect their thinking. If Johnson managed to pass a deal without them, the limits of their influence would be exposed.

Also crucial to Johnson’s chances are the Labour Party. Around 30 Labour MPs have in the past been willing to sign letters urging a Brexit deal, but far fewer have ever voted for one. This month, though, 19 signed a letter urging the EU to work with Johnson. That might indicate a willingness to actually vote with him.

If Johnson could line up the Spartans, the DUP and more than a handful of Labour MPs, he would have a chance of getting his deal through.

Many of the 22 MPs who left the Conservatives last month would be ready to vote for a deal, though not all. If it’s a deal that they think would result in a distant relationship with the EU, their support isn’t guaranteed.

It’s far from a certainty. Much depends on what the actual agreement, if there is one, looks like. But for Johnson, for now, the silence is golden.

To contact the reporter on this story: Robert Hutton in London at rhutton1@bloomberg.net

To contact the editors responsible for this story: Tim Ross at tross54@bloomberg.net, Thomas Penny, Robert Jameson

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