Jeremy Corbyn has backed cross-party plans to delay a vote of no confidence in Boris Johnson and prioritise rebel MPs’ attempts to use legislation to stop a no-deal Brexit, with plans set to be agreed by the end of the week.

In a meeting with opposition parties convened by the Labour leader, Corbyn opened the discussion by reassuring MPs that Labour would not seek a premature vote of no confidence that might stymie legislative efforts to stop no deal. But there could yet be a conflict over who should lead the push for legislation to stop a no-deal Brexit.

Corbyn said he would “propose the parliamentary process which would mean the legislation can be laid”, though other opposition MPs have made it clear they believe the moves must be led by backbenchers.

Key opposition MPs will convene smaller meetings to discuss plans for legislation over the next 48 hours and party leaders hope to speak again by the end of the week, according to sources.

MPs’ efforts were given a fresh sense urgency on Tuesday evening as rumours swirled at Westminster that the privy council of senior ministers was preparing to meet the Queen at Balmoral this week, perhaps as soon as Wednesday.

Leaked emails revealed at the weekend that the prime minister had sought legal advice about proroguing parliament for five weeks from early September, when MPs are already due to break briefly for party conferences.

A new session of parliament would then begin with a fresh Queen’s speech packed with manifesto-friendly measures on or around 14 October.

Such a move would have to be approved by the privy council. It would give MPs little chance for parliamentary manoeuvring, but could just about allow time for a vote on any reworked deal Johnson manages to strike with the EU27, before the crucial European council meeting on October 17. One source suggested something like this timetable could be on the agenda at the privy council meeting.

Speculation that Johnson could call an early general election was also heightened on Tuesday when the Treasury abruptly cancelled a major speech by the chancellor, Sajid Javid. Instead, the Treasury announced that the one-year spending review, setting out the government’s economic priorities, is to be fast-tracked to 4 September – the day MPs return to parliament – in a sign that the government wants to highlight a new policy agenda before a potential autumn election.

An agreement to focus efforts on passing legislation to stop a no-deal Brexit was made at Tuesday’s meeting, attended by the Scottish National party’s Ian Blackford, Jo Swinson of the Liberal Democrats, the Green party’s Caroline Lucas, Plaid Cymru’s Adam Price and Liz Saville Roberts and the Independent Group for Change’s Anna Soubry.

Speaking after the meeting, Corbyn said he would “put forward a proposal which will make sure that parliament is able to debate a legislative way of preventing the government crashing us out with no deal … the legislation will be laid by people from all of the opposition parties and will be supported by some Conservative MPs as well.”

MPs are planning on using the same tactics as they did earlier this year when rebels seized control of the order paper and passed a bill led by Yvette Cooper and Oliver Letwin that mandated an extension to article 50.

Moves are also planned to force the publication of damaging no-deal preparation documents to win public backing for efforts to prevent a no-deal departure, as well as other parliamentary manoeuvres to try to block any proposed prorogation of parliament.

Parties also discussed opposing holding the regular parliamentary recess over the party conference period in late September, though a Labour source said nothing had been agreed.

In a joint statement published by Labour after the meeting, which appeared to retreat from the party’s initial offer to call a vote of no confidence and establish a caretaker government led by Corbyn, the party leaders said they “agreed on the urgency to act together to find practical ways to prevent no deal, including the possibility of passing legislation and a vote of no confidence”.

The Labour leader insisted later that the option of a motion of no confidence remained on the table and could be explored simultaneously. “It’s nothing to do with whether people like me or not,” he said. “The priority is to ensure we don’t crash out of the EU. And we will put a motion of no confidence at a time of our choosing.”

Although Letwin, Dominic Grieve, and Caroline Spelman, all prominent Conservatives opposed to Brexit, were invited to the meeting, no Tory MPs attended.

Corbyn had made an offer to opposition MPs that he would lead a caretaker government for a short period to negotiate an extension to article 50 and then call an immediate general election in which Labour would campaign on a platform of offering a second referendum.

This has been rejected by the vast majority of Conservatives, as well as the Lib Dems. Rebel Conservatives and former Tories including Nick Boles, some of whom have been key movers in efforts to stop no deal, have insisted parliamentary legislation should be the focus. It is understood Soubry, a former Conservative MP, made a forceful case that legislation had to be a priority.

Boles had said he was deeply concerned that Corbyn would attempt to trigger a no-confidence vote too early and wrote to the Labour leader urging him to “declare publicly that you will not facilitate an election before an extension of article 50 has been secured and a no-deal Brexit has been averted”.

After the meeting, Corbyn wrote to 116 backbench Conservative and independent MPs including Theresa May, Philip Hammond, David Lidington and Greg Clark, urging them to back the cross-party efforts against no deal.

Labour said it had highlighted MPs who had voted against no deal on 27 March when voting for an extension to article 50. “We know there is a majority in parliament against no deal,” he wrote. “I am writing to you to offer to work together, in a collegiate, cross-party spirit, to find a practical way to prevent no deal.”

Soubry said there was “no debate” that the legislative route was the best way forward. “A vote of no confidence is absolutely the last resort. The best way of stopping us crashing us out on 31 October is to pass legislation,” she said. “It is a very serious step to win a vote of no confidence and can only be done if he [Corbyn] is certain of winning it.’”

The SNP’s Blackford called the meeting “positive and productive” and emphasised his party’s belief that legislation should be a priority. Lucas and Swinson also emphasised their support for the plan.