Rishi Sunak's new Brexit deal will face its first test in the Commons next week when MPs vote on a key part of it.
The Prime Minister is desperately trying to unite his deeply-divided party behind the Windsor Framework deal he reached with the EU last month.
On Wednesday the so-called Stormont Brake - aimed at preventing changes to EU law or the introduction of new legislation in Northern Ireland - will be put before the House.
No10 said this is at the "heart" of the Windsor Framework - but it is unclear which other aspects of the deal MPs will get to vote on in the future.
The agreement followed a complex round of negotiations aimed at undoing the worst excesses of Boris Johnson's botched Brexit deal, which caused devolved government to collapse in Northern Ireland.
Predictably Mr Johnson has been a thorn in Mr Sunak's side, saying he would "find it difficult to vote for something like this myself".
The vote will be held immediately after PMQs - shortly before Mr Johnson is due to give evidence to a committee probing him over Partygate at 2pm.
It is not clear if there will be any overlap, but the Prime Minister's official spokesman responded "no" when asked if it was timed as a distraction.
Mr Sunak has previously pledged that MPs will get their say, and his spokesman told reporters: "We said Parliament would have its say on the framework.
"This vote honours the Prime Minister’s commitment to provide MPs with the opportunity to vote on the new arrangements."
Commons Leader Penny Mordaunt confirmed that a statutory instrument on the Stormont break section of the Windsor Framework will be heard next week.
It comes despite the DUP - which collapsed powersharing in protest over the botched Northern Ireland Protocol - still deliberating whether it accepts the agreement.
The DUP has however hinted there could be issues with it, saying it does not deal with "fundamental problems".
And Mr Sunak could face opposition from within his own party.
In a speech laced with bitterness on March 2, Mr Johnson said: "This is not about the UK taking back control and although there are easements this is really a version of the solution that was being offered last year to Liz Truss when she was foreign secretary.
"This is the EU graciously unbending to allow us to do what we want to do in our own country, not by our laws, but by theirs."
And it's not clear if hardline Brexiteers within Tory ranks will be satisfied with what they've read.
The European Research Group of Tory Brexiteers has commissioned a so-called "star chamber" of experts to consider the deal before it decides how to vote.
Mark Francois, the group's chairman, said: "We are still awaiting the outcome of the star chamber's detailed legal audit of the Windsor Framework, which of course includes the Stormont brake.
"We now hope to see this completed before next Wednesday and members of the group will no doubt pay close attention to the star chamber's conclusions, prior to any vote."
But Labour has said it will support the government to get the deal through.
Keir Starmer told MPs last month that Labour would not "snipe" or "play political games". But he urged the latest Prime Minister to repay that faith by being "utterly unlike his predecessor".
He said that Mr Johnson's 2020 agreement had led to the collapse of power-sharing in Northern Ireland, leaving the country without an effective devolved government.
But he urged the PM not to act in the same way Mr Johnson did, saying: "So, when presenting what this agreement means in practice, I urge the Prime Minister to be utterly unlike his predecessor.
"Do not pretend the deal is something it is not. Where there are trade-offs to be made, argue the case for them.
"Treat unionists with the respect of frank honesty, not the contempt of bluster."
On Tuesday, a meeting of EU ministers at its General Affairs Council is expected to sign off on the pact.
