LONDON — Michel Barnier’s pincer is about to close on Theresa May — with the help of Jacob Rees-Mogg’s band of hard-line Brexiteers.

As U.K. MPs prepare to break for the summer, there is growing sense in Westminster that the only realistic option likely to be left open by the time they return in September will be total surrender to Brussels.

That would mean staying in the EU’s single market for the softest of Brexits to avoid either a "no-deal" scenario, likely to be impossible to get through the House of Commons, or a customs border being erected between Northern Ireland and the rest of the U.K. — the only other option the EU's chief Brexit negotiator has said he will accept.

Without a dramatic course change from Brussels or leading Tory Brexiteers, only one route to Brexit remains that is likely to be palatable to the EU and could also carry a majority in the House of Commons — though it is unlikely May could survive it as prime minister. Capitulating to Brussels' wish to see the U.K. stay in the EU's single market may yet prove to be the U.K.'s best chance of avoiding a crisis, at least as a temporary solution, according to two government ministers who spoke on condition of anonymity.

A series of crunch moments in recent weeks have exposed the precariousness of the U.K. prime minister's position. Brussels has shown little enthusiasm for May's compromise Brexit white paper since its publication earlier this month, while her own MPs reacted with open hostility amid Cabinet resignations and angry speeches denouncing her "sellout." Barnier, the EU's chief negotiator, said Friday it is almost impossible to split goods and services as the plan proposes.

The existential problem for May is that parliamentary arithmetic renders potential escape routes almost impossible.

Even if May manages to win agreement for her plan with Brussels, she will struggle to get it through the House of Commons. Recently departed Foreign Secretary Boris Johnson said it amounts to “Brexit in name only,” which he could not support. Former Brexit Secretary David Davis called for the prime minister to rip up her white paper and start again.

“[The Chequers plan is] dead,” one pro-EU and usually loyal government minister said. “The party can’t stomach it.”

The existential problem for May is that parliamentary arithmetic renders potential escape routes almost impossible. A complete abandonment of her red lines would spark open revolt in her party. A "no-deal" divorce is overwhelmingly opposed by MPs. And MPs believe a snap general election would likely split the Tory Party down the middle and pit the prime minister against Conservative activists.

“She would have to put her deal to the country and deselect all the MPs who did not agree,” one senior Conservative MP said of the prospect of May fighting an election asking for a mandate for her Brexit deal. “It would be a bloodbath and there’s no way she would want to do that. She is deeply wedded to the Conservative Party.”

In any case, by splitting her party, May would hand a clear advantage to the opposition Labour Party, undermining the reason to call an election in the first place.

Crash-out Brexit

In Berlin Monday, the new Foreign Secretary Jeremy Hunt said there was now “a very real threat of 'no deal' by accident,” which he said would “change British public attitudes to Europe for a generation.”

However, it is difficult to envisage a scenario in which Britain “accidentally” falls out of the EU on March 29, 2019. Pro-EU Tory MPs succeeded in winning a concession from the government in the final stage of the EU (Withdrawal) Act through parliament last month, which means the government must put a no-deal scenario to a vote in the House of Commons.

According to the act, the prime minister must make a statement to MPs before the end of January 21 if no agreement can be reached with Brussels. Within 14 days of this statement she must then lay a motion in the House setting out what she proposes to do next.

While this motion is not legally binding, politically it would be almost impossible to ignore without sparking a constitutional crisis.

According to Tory and Labour MPs, there is currently no majority for “no deal.”

“There’s no way I’d support it,” one loyal government minister said. “Can you really imagine [Chancellor] Philip Hammond or Jeremy Hunt supporting ‘no deal’ either? It’s not going to happen.”

If May cannot command a majority in parliament for her government's central policy, it is unlikely she would survive as prime minister for very long.

Soft Brexit on the table again

In the absence of alternatives, some Conservative MPs and activists are turning to the softest of Brexits, ruled out by May's government early in negotiations, that would mean the U.K. remaining in the EU's single market by joining the European Free Trade Association (EFTA) along with Switzerland, Iceland, Norway and Liechtenstein.

Two government ministers said the idea is gaining traction among Conservative MPs looking for an escape route from the looming crisis.

The influential ConservativeHome website for Tory activists set hares running last week when it floated the controversial soft-Brexit “plan B,” which is notable for not being immediately shot down.

Because May has ruled out this option on multiple occasions, it would likely require a new Tory leader to pursue it.

Under the plan, once out of the EU, the government would immediately begin preparations for the U.K. to leave the single market on World Trade Organization terms if the EU continues to refuse to negotiate a U.K.-wide free-trade deal that does not include a customs border between Great Britain and Northern Ireland.

By exiting the EU, the U.K. would have removed the ticking clock leverage of the Article 50 process, which sets a two-year time limit for negotiations, allowing a new prime minister to prepare for WTO trading terms in good time should discussions with Brussels not result in a deal.

However, one fly in the ointment is the risk of a downturn caused by the shifting from single market membership to World Trade Organization terms governing trade with the EU. To avoid such an economic hit ahead of the next general election scheduled for 2022, the government would want to delay the switch until afterward.

Leave voters want to see a certain type of Brexit, but most people might say they’ve had enough of all that and then you’re stuck" — Brexiteer Conservative aide

But some Tory MPs fear that if Labour were to win, they would decide to make such "temporary" single market membership permanent.

Aides close to leading Brexiteers said this fear is real. “The nervousness is we would never get out of it. Leave voters want to see a certain type of Brexit, but most people might say they’ve had enough of all that and then you’re stuck. The [Norway option] is perceived as sellout,” said a Brexiteer MP.

A second aide to a high-profile Brexiteer said the plan does not have enough support among leading Leavers. “DD [David Davis] was pouring piss on it,” the aide said, insisting that to work it would probably require the Conservative membership to endorse it in a leadership contest sparked by a May resignation.

Unless the EU and Britain’s hardline Brexiteers change course, there may not be another option.