LONDON — She got there in the end — and just about held the line.

After a tortuous 24 hours of back and forth with her Brexit secretary, U.K. Prime Minister Theresa May emerged Thursday lunchtime with an Irish “backstop” plan for Brussels that Downing Street hopes will form the beginning of a breakthrough in the Brexit talks.

And she got there without any Cabinet resignations. Yet.

The critical moving part of the negotiations going into the European Council summit at the end of the month has been the U.K.'s alternative Ireland backstop plan, which is designed to prevent a hard border in Northern Ireland in the event that negotiators cannot come to an agreement. Both sides agreed the need for a backstop back in December, but in February, May roundly rejected the EU’s proposal, which amounted to a customs border between Northern Ireland and the rest of the U.K.

Now we have May's alternative.

That there is any date in the document at all is Davis' doing, but whether it amounts to much in practice is less clear.

But not without a bruising fight at the top of government that strained relations with David Davis close to breaking point. He staked his reputation on a battle of wills with the prime minister over the inclusion of a cutoff date to avoid the prospect of the U.K. remaining indefinitely in a kind of EU limbo.

His former ministerial colleague and fellow enthusiastic Brexiteer David Jones referred to that dreaded outcome in a BBC interview Wednesday morning as a "'Hotel California' scenario — we’d have checked out but we wouldn’t be able to leave."

After an intense morning of talks between May and Davis, the published plan does mention a date — December 2021, a year after the end of the already agreed transition period. But it is apparently only an aspiration for when the U.K. "expects" the future customs arrangement to be in place.

That there is any date in the document at all is Davis' doing, but whether it amounts to much in practice is less clear. Although this was a victory for Davis, won by threatening to resign, it could prove pyrrhic if it prompts a rejection of the plan by Brussels.

Fair hearing

The six-page document — drawn up and published by the Cabinet Office (where May’s chief EU adviser Olly Robbins has his power base), not Davis’ Brexit department — is peppered with nods to the Euroskeptics, including the crucial new "time limiting" final paragraph, No. 26.

Crucially, while keeping the U.K. within the EU's tariff regime, the plan frees the country from the Common Commercial Policy. That means that in theory, it could strike its own trade deals in areas that don't require tariffs, i.e. services. The text makes clear that Britain would be able to ratify such trade deals while still subject to the backstop.

It also says that the U.K. wants to continue to benefit from existing EU trade deals, as well as negotiating a “mechanism to ensure that the U.K. national interest is represented” in any free-trade agreements the EU may sign while the backstop applies.

There are concessions to Brussels too, with acknowledgements that the U.K. cannot unilaterally decide which customs arrangements it wants in place if and when the backstop comes to an end and that "it may make sense for U.K. courts to look at the appropriate [European Court of Justice] documents."

The bottom line though, is that May — and her chief Europe adviser Robbins — emerged, broadly, with what they wanted: an offer which they feel stands at least a chance of a hearing in Brussels.

Now the ball is in the EU’s court.

Chief negotiator Michel Barnier gave it an initial cautious welcome on Twitter. He said he would apply three tests: “Is it a workable solution to avoid a hard border? Does it respect the integrity of the [single market and customs union]? Is it an all-weather backstop?”

The meaning of the final phrase will likely become clear at a press conference on Friday in Brussels.

Other EU figures were more forthright in their criticism. The Parliament's Brexit coordinator Guy Verhofstadt tweeted: "A backstop that is temporary is not a backstop, unless the definitive arrangement is the same as the backstop."

One EU official working on Brexit pointed out that the aspirational cutoff date was earlier than some U.K. estimates for the time it would take to put customs infrastructure in place on the border, “which means that it won’t be ready in time for their own deadline." A European Parliament official who works on Brexit simply called the plan "cherry-picking."

EU negotiators have previously been categorical that any backstop arrangement must be Northern Ireland-specific. In a briefing for journalists in Brussels two weeks ago that provoked a strong reaction in London, a senior EU official said: "The regulatory alignment option is not available on an all-U.K. basis because it would amount to selective participation in the single market."

On that score, the new U.K. proposal looks a long way from something that Brussels can accept.

Suspect timing

The breakthrough in London came just hours before May headed to Canada for what threatens to be a fractious G7 summit with Donald Trump, Angela Merkel and other world leaders.

For Brexiteers, however, the timing is more suspect, coming just days before the most important legislative House of Commons showdown of the year so far, with the EU (Withdrawal) Bill subject to a series of crunch votes over two days next week.

Euroskeptic Tory MPs — led by Jacob Rees-Mogg — mostly resisted the urge to pile in behind Davis over the backstop fight because they are determined not to rock the boat at such a crucial time during the passage of the government's flagship Brexit legislation. They don't want to alienate pro-European colleagues, whose votes they need to help strip out 15 amendments inserted into the bill by the House of Lords.

Rees-Mogg himself was noncommittal in his view of the backstop proposal on Thursday afternoon, saying: “It is a negotiating document and nothing is agreed until everything is agreed.”

Davis, while extracting a symbolic concession, has pulled himself clear from the onrushing prospect of resignation, alive to keep fighting the Brexiteer cause on the inside.

He and the rest of the government will argue that the backstop is just a last resort in any case. The government wants to solve the Irish question by negotiating a comprehensive future relationship with the EU.

But if the early reaction from Brussels to the U.K.'s backstop plan is anything to go by, Davis and his Cabinet colleagues may have more difficult decisions to make sooner than they would like.

David Herszenhorn, Maïa de La Baume and Jacopo Barigazzi contributed reporting.