With the EU Withdrawal Bill due back in the Commons next week, the row over plans to give MPs a meaningful vote on the final Brexit deal has turned into a game of very high stakes.

Dominic Grieve, the leader of the Tory rebels seeking to amend the government's flagship Brexit legislation so that the Commons could direct ministers in negotiations should it reject a deal, admitted on the BBC's Sunday Politics this afternoon that their efforts to do so could topple Theresa May.

"We could collapse the government, and I assure you that I wake up at 2am in a cold sweat thinking about the problems that we have put on our shoulders. The difficulty is that the Brexit process in inherently risky, really risky. Risky to our economic wellbeing, risky to our international relationships and ultimately to our national security."

Such candour is striking and will guarantee the mutineers headlines tomorrow. But it doesn't follow that Grieve's admission is necessarily good news for their cause in the immediate term: ensuring enough Conservative rebels back his plans to give the Commons the right to direct the government in negotiations in the event of no or an unsatisfactory deal, rather than the right to vote for or against an unamendable and non-binding Commons motion, the abortive compromise proposed by May.

Talking up the potential for their actions to destabilise the prime minister is bad for the rebels. They did not vote against the government on the issue of a customs union last week for that precise reason – doing so, they believed, would have enraged Brexiteers and jeopardised May's leadership at a dangerous time for party and country.

Conversely, rebelling on the meaningful vote has hitherto been justified on the grounds that it's a non-ideological, procedural device that wouldn't result in the political upheaval government defeats on the single market and customs union would. In admitting that their manoeuvres could in fact topple the government, Grieve may well have made rebelling on the meaningful vote a much harder sell for MPs who might have been convinced otherwise.

One such MP is Tom Tugenhadt, the chair of the foreign affairs select committee who rebelled on previous amendments to the Withdrawal Bill but sounded bearish on the meaningful vote issue earlier this week. “I think we're going to get a meaningful vote anyway," he said. “The meaningful vote is going to be either the government’s deal is accepted, in which case that’s the meaningful vote to accept it, or it is not accepted, in which case, frankly, there’s going to be a new government.”

Perhaps unintentionally, Grieve gave succour to that argument this afternoon. The 15 to 20 MPs who were willing to back the Lords amendment on the meaningful vote last week could yet decrease in number as a result. As unlikely as it seemed last week, the government could yet see the Withdrawal Bill pass unscathed by rebels on customs, the single market, and the meaningful vote.