Boris Johnson's campaign aides have sought to play down reports that they are considering plans to prorogue Parliament in late October – a move which could prevent MPs stopping a no-deal Brexit.
The Tory leadership frontrunner's team is said to be looking at scheduling a Queen's speech for early November, according to Sky News.
Parliament would be unlikely to sit for a week or two ahead of the speech, which could hamper MPs' chances of blocking a no-deal Brexit if a deal had not been passed by that point.
A source close to the campaign told PA the team was "discussing everything as an option", but Mr Johnson wanted to secure a deal with Brussels and avoid a no-deal exit.
Tory former minister Guto Bebb, a prominent Remain supporter, said he believed Mr Johnson's campaign was "quite seriously contemplating" suspending Parliament.
He told Sky News: "If you decided to do a Queen's speech in early November, you'd prorogue Parliament in mid-October so we didn't sit for the final two weeks in October.
"It would basically mean that a no-deal Brexit, which has no democratic mandate whatsoever, would be imposed upon the people of this country without this House sitting.
"And I think that would be an outrage to our democratic traditions, it would be unacceptable and the worst part is I believe they are quite seriously contemplating doing just that."
Unlike contest underdog Jeremy Hunt, Mr Johnson has refused to rule out suspending Parliament to force Brexit through against the will of MPs.
On Monday he said the problem with the controversial Irish backstop was "fundamental", and suggested he would not accept tweaks such as a time limit or a "unilateral escape hatch".
Dominic Grieve accused Mr Johnson of further radicalising on Brexit and leaving the UK with "starker" prospects by trying to appease hardliners in a strengthening of his stance on the backstop.
The former attorney general also accused him of making a "disgraceful" suggestion which would "spell the end of democracy as we know it".
On Tuesday, Mr Grieve warned whoever becomes the next prime minister that their government will collapse if they pursue a no-deal departure from the EU.
Mr Grieve said Mr Johnson confirmed that hardliners would "put up another obstacle" if anyone was able to solve the issue because it is being "used as an excuse because of this radicalisation".
"When challenged and confronted, he radicalised even further and excluded any possibility of trying to negotiate some way out of the backstop at all. It had to go in its totality," Mr Grieve said.
"The consequence of that is (to) make ... the choices starker and starker.
"I've always been willing as a politician to listen to people willing to come up with credible compromises, but what I've found so staggering about the Conservative leadership (contest) is it has been played to a tune of growing extremism."
Speaking alongside Mr Grieve at a second referendum campaign event, Labour MP Margaret Beckett called the candidates' backstop pledges "terrifying" and accused them of throwing "the Irish situation under a bus".
"Nobody can say that that situation is now so peaceful it's inconceivable that there will be further problems in the future. I think that's an extraordinary demonstration of lack of responsibility to the country," she said.