Speculation is mounting that Boris Johnson could seek a snap general election if backbench rebels succeed in passing a bill to delay Brexit, with a Downing Street source saying the issue would be treated as “an expression of confidence” in the government.

Johnson’s cabinet ministers are being summoned for an emergency cabinet meeting on Monday afternoon, before the prime minister addresses Conservative MPs at a No 10 drinks reception.

Senior sources among the cross-party group of rebels say they believe Johnson could seek a snap general election as early as Wednesday, asking for the two-thirds majority needed in the Commons under the Fixed-term Parliaments Act.

The sources suggested the vote would come with a commitment that polling day would be before 31 October, though the date would ultimately be in the control of the government.

The Downing Street source confirmed Johnson would see cabinet ministers before the MPs’ reception, saying they would “discuss the government’s response to MPs seeking to take control of legislative agenda away from the government and handing it to the opposition and Corbyn without the consent of the people”.

The source added: “The view is that tomorrow’s possible vote is an expression of confidence in the government’s negotiating position to secure a deal and will be treated as such.”

It is understood that an attempt to seek a general election is unlikely to be announced immediately, but the cabinet will discuss a number of possible strategies after the upcoming votes in parliament.

Tory whips are attempting to draw a distinction between MPs who are voting with conscience to stop no deal and those who will vote to hand control of the order paper to rebel MPs in order for a bill to pass.

It is the latter group that No 10 says it believes are in effect voting against the government in a confidence vote – by taking the power to control parliamentary business away from a Conservative administration – and it is those MPs who will lose the whip.

The Guardian has spoken to at least 18 Conservative MPs who have said, privately or publicly, they have not been deterred from voting to stop no deal, despite threats of deselection and a possible early election.

Those include the former cabinet ministers David Gauke and Philip Hammond and the former ministers Alistair Burt, Stephen Hammond, Richard Harrington and Guto Bebb.

One source close to the rebel group said the mood had hardened, especially since the cancellation of a meeting with Johnson on Sunday night.

“This is a pathetic attempt to find an excuse for a general election,” one former cabinet minister said. “Ironically this is doing what Corbyn wants – is Cummings a sleeper agent?”

The rebels, spearheaded by Gauke, Hammond and the backbenchers Oliver Letwin and Dominic Grieve, are expected to attempt to take control of the Commons agenda on Tuesday, when parliament returns from the summer recess.

They would then seek to push through a bill mandating an extension to Brexit before parliament is suspended at the end of the week.

Earlier on Monday, Gauke predicted the expected vote on the backbench bill could be “very tight” but said government threats to deselect Conservative MPs who defied the party on the issue could increase the number of rebels.

However, several Tory MPs who have been vocally against no deal are not prepared to vote to give the rebels control of the order paper, especially given the briefing from No 10 that this would be seen as a confidence measure.

The Guardian understands this includes MPs such as Dame Caroline Spelman, one of the sponsors of a motion against no deal earlier this year, and the former Foreign Office minister Alan Duncan.

Gauke said he had written to the attorney general, Geoffrey Cox, and his successor as justice secretary, Robert Buckland, asking for clarification about comments by Michael Gove, chancellor of the Duchy of Lancaster, who declined to rule out the idea that the government could simply ignore the bill if it were passed by MPs.

“It would be very helpful if the government could clarify that they believe in the rule of law,” he told BBC Radio 4’s Today programme.

Gauke declined to say what the bill could seek to achieve. But another leading rebel, the former Tory MP Nick Boles, said a likely consensus plan would be to delay Brexit by a couple of months from 31 October, to allow enough time for a deal to be reached but not enough time for a second referendum.

The stakes for would-be Tory rebels became markedly higher at the weekend when Downing Street confirmed Conservative MPs who backed the no-deal blocking measure could lose the party whip, meaning they would be unable to stand for the Tories in the next election.

Downing Street has also repeatedly refused to say whether Johnson could simply ignore the backbench legislation.

Asked about the general principle, Johnson’s spokesman repeated a point made by Gavin Williamson in broadcast interviews earlier on Monday: “The education secretary dealt with this this morning when he said every government adheres to the law.”

But pressed repeatedly on whether this meant No 10 would commit to abiding by a backbench bill designed to thwart a no-deal Brexit, the spokesman declined to do so.

On Sunday, Gove, who is in charge of no-deal Brexit preparations, ignited the row by declining to rule out the idea that the government could ignore such a law. “Let’s see what the legislation says,” he told BBC One’s The Andrew Marr Show.

On Gove’s comments, the No 10 spokesman said: “I think he was very clear with the point he was making, which was that we haven’t seen any legislation yet and that the government will need to look at any legislation brought forward to establish what it does or doesn’t require.”

Pressed on this, he said: “In relation to this specific point, we’re going to have to look at the legislation which is brought forward. We haven’t seen what’s been put forward yet. The people who are promoting it have not been willing to share that.”

The spokesman denied Gove’s comments amounted to a “pick-and-choose” approach to abiding by the law. “He was simply saying in relation to this particular piece of legislation that we haven’t seen it yet,” he said.

A Downing Street source later sought to play down the significance of what Gove said, saying it could simply be a case of ensuring the bill was possible in practical terms. The source pointed to the example of backbench amendments bringing equal marriage and abortion to Northern Ireland, where some of the stated timetables were not possible.

• This article was amended on 3 September 2019 to remove suggestions that the prime minister has the power to call a snap election. The Fixed-term Parliaments Act makes the calling of a general election outside five-year terms the decision of the House of Commons, not the prime minister.