Speaker says he has told officials to to block any bids to table unchanged proposal

Theresa May’s hopes of putting her Brexit deal to a third meaningful vote have hit another obstacle after John Bercow said parliamentary procedures could not be used to present it unchanged, even as more senior Eurosceptics seem to be getting behind the agreement.

Amid speculation the prime minister is making a private pact to set a date to stand down when the deal goes through, more than 20 Conservative Eurosceptics have publicly suggested they will change their minds because they do not want a softer Brexit.

Brexit: MPs to vote on alternative plans as speculation mounts May could announce decision to quit - live news Read more

Even if this many MPs in the European Research Group (ERG) switched, the vote would be extremely tight, but there was mounting speculation the government could table it on Thursday or Friday.

This plan, however, could be scuppered after the Speaker told ministers he stood by his ruling that the twice-defeated motion could not be put to MPs again without significant change.

Bercow said he had instructed officials to block any attempts to put forward the same or similar plan using procedural rule changes, for example, by using a vote by MPs to instruct the Commons to overlook the rule behind his block.

“I understand that the government may be thinking of bringing meaningful vote three before the house either tomorrow or even on Friday, if the house opts to sit that day,” Bercow told the Commons before the start of a debate on indicative votes on Brexit.

“Therefore, in order that there should be no misunderstanding, I wish to make clear that I do expect the government to meet the test of change. They should not seek to circumvent my ruling by means of tabling either a notwithstanding motion or a tabling motion.

“The table office has been instructed that no such motions will be accepted. I very much look forward, colleagues, to today’s debate and votes which give the house the chance to start the process of positively indicating what it wants.”

Bercow’s original ruling, earlier this month, plunged the Brexit plan into procedural chaos. Citing Erskine May, the official guide to parliamentary procedure, the Speaker said the bar on the same measure being brought more than once in the same parliamentary session was a “strong and longstanding convention” dating back to 1604.

If the vote does eventually happen, May will require support from the Democratic Unionist party and almost all the ERG to win. She could afford to do without around 10 “Brexit ultras”, with the exact number depending on whether any more Labour MPs, such as Jim Fitzpatrick, end up folding as well.

There are currently at least 15 Conservative MPs who appear implacably opposed to changing their minds, including six who are pro-remain, such as Justine Greening and Sam Gyimah.

A frantic campaign is under way among some Eurosceptics to persuade the last of their colleagues to get behind May’s deal for fear of there being no Brexit at all, as MPs prepared to vote for eight alternative options, from a Norway-style departure to revoking article 50, or holding a second referendum, on Wednesday evening. They can choose to support as many as they want.

Iain Duncan Smith, the former Tory leader, is said to be in talks to persuade May to privately agree to stand down if the withdrawal agreement is passed. She would then publicly announce a departure date, with MPs reserving the right to vote down her deal at the second reading if she did not honour the pledge to announce her resignation.

May is due to address a gathering of Conservative backbenchers on the 1922 Committee at 5pm, leading to rumours that she will declare her timetable for leaving office. However, people around the prime minister are understood to be worried that openly saying she will quit after Brexit will look like a stitch up in exchange for votes, while some senior ERG MPs are keen to make her departure look dignified rather than forced.

Boris Johnson, the former foreign secretary, has given the most overt hints that he could back the deal if May made way for a successor.

He described it as a “terrible deal, something which I bitterly opposed for a long time”. However, he said he needed “to see that the second phase of the negotiations will be different from the first” and highlighted the “appreciable risk” that not voting for the deal could lead to no Brexit.