A prominent pro-Remain MP has called for urgent talks about an anti-Brexit alliance, signalling she is prepared to stand down if necessary to help it happen.

Sarah Wollaston, who resigned from the Conservative party over its Brexit stance, said the threat of a “populist” autumn election meant there was now a sense of urgency for Remain parties to come together to fight the danger of a hard Brexit.

“We do not have the luxury of time,” she told the Observer. “An election could easily happen in the autumn and we have to be prepared for that, rather than trying to put something together in a hurry and find it’s too late. There should be a sense of urgency.

“At both local and national level, the pro-Remain parties need to be talking about how a Remain alliance could work in practice, looking at all the available data on how it could be done, and which party is best placed in each seat. It won’t work everywhere, nor will the model necessarily be the same in every seat, but I think Remain voters want to see a progressive, Remain alliance across the country.”

Her comments come amid predictions that a Boris Johnson victory in the Tory leadership contest would precipitate an autumn election, as a result of his vow to leave the EU at the end of October, even without a deal.

An attempt to forge a Remain alliance during the Peterborough byelection last month broke down, despite talks between the Lib Dems, Greens and Change UK. However, Jo Swinson, one of two candidates to become the next leader of the Lib Dems, has said she wants to work with other groups and alliances to stop the UK leaving the EU through a second referendum.

Asked about her future in her Totnes constituency, Wollaston said she would “welcome the opportunity” to run again if local parties thought she was the best unity candidate.

However, she added: “I would not want to obstruct them or get in the way, either. I would not run against a Remain-alliance candidate. I would stand aside in those circumstances, but I would love to carry on my work representing the Totnes constituency and fighting against a disastrous no-deal Brexit.

“It looks like [we] could be heading for a populist election campaign and we need to be in as strong a position as possible should that happen.”

Wollaston is one of six MPs who defected to join pro-Remain Change UK, and then left the group to sit as an independent. One of the others, Chuka Umunna, has since joined the Lib Dems, who were the strongest pro-Remain party at last month’s European elections.

Wollaston, chair of the Commons health select committee, said she would wait to see who the Lib Dems appointed as their next leader before deciding whether to consider joining the party. “I am currently sitting as an independent and that fits well with my work as a select committee chair,” she said. “I am waiting to see how the party’s leadership election plays out before making any decisions.

“Jo Swinson seems to have indicated she is more open to alliances.”

She said she had been alarmed by the number of Tory MPs who were against a no-deal Brexit, but had been unwilling to break party unity to stop it happening. “It has amazed me that so many MPs seem to have put the future of the Conservative party above everything else and that they would rather a no-deal Brexit over a Jeremy Corbyn government,” she said. “But their actions mean we could end up getting both – if we crash out, with all the real-world consequences and the Conservatives losing all credibility on the economy, then have an election in which Labour wins and it gets even worse.”

She urged Corbyn to change Labour’s stance to become a clearly anti-Brexit party. However, she questioned whether voters would trust the party should it change course now.

“I would love to see Labour change its position and say unequivocally that it backs a second referendum and would campaign as a pro-Remain party,” she said. “But even now Jeremy Corbyn is still resisting that, supported by a small number of people around him. The question is, even if the party did change its position now, how credible would that be? Locally, Labour candidates may back Remain, but it is a problem if that is not the party’s clear official position.”