The pro-left MPs on Saturday predicted that they would get enough support from all parties to hold a second Brexit referendum while new doubts were raised about whether Boris Johnson could reach an agreement with the EU that can go through Parliament.

The push for a second vote seemed to be gaining momentum before what appears to be a dramatic "super Saturday" showdown in Parliament next weekend. This House of Commons emergency session, convened by Johnson, will be held after a crucial EU summit in Brussels on Thursday and Friday. This will coincide with a pro-referendum march in London, to which one million people could participate, according to the organizers.

On Saturday, Johnson's chances of winning an agreement that will win crucial support from the 10-member DUP appeared to be increasingly questionable, while Nigel Dodds, the party's leader at Westminster, questioned the key elements of the proposed agreement – including the idea of ​​Northern Ireland. to be in a form of post-Brexit customs partnership with the EU.

"Northern Ireland must remain in a complete customs union of the United Kingdom, a full stop," said Dodds. Asked that the ideas discussed behind closed doors by the UK government and the EU might work, he added: "No, it can not work because Northern Ireland must continue to be an integral part of it. of the British Customs Union ".

For Johnson to have any chance of reaching an agreement by Parliament, he will need the DUP to support him firmly. Many conservative members of the pro-Brexit European reformist group of reformists have said they will take the lead in the DUP.

Nigel Dodds and Arlene Foster

Nigel Dodds and Arlene Foster's support for any Brexit deal will be crucial for the Prime Minister. Photography: Rebecca Black / PA

In the hope of reaching an agreement on a knife, the Labor Party is supposed to be ready to convince its members to support a second referendum. "We think we are getting closer to the majority that it needs," said one source involved in the effort. "The task now is to maximize this majority and see if Johnson finally recognizes that it's also an issue for him."

It is likely that conservatives and ex-conservatives will further support a second referendum if the government fails to reach an agreement, and that the alternative is a Brexit without agreement, key figures announce plans referendum on any agreement reached between the Prime Minister returns with also gaining support.

On Saturday night Labor MP Peter Kyle said it was presumed that an agreement with Johnson would be bad for the economy and that enough MPs would insist that it be put to a vote public confirmation. "If Johnson signs an agreement that offers less access to European markets than Theresa May's – and this seems to be precisely what is proposed – the idea of ​​moving through the Commons would be tantamount to a suicide mission," said he.

"If such an agreement is proposed, we will amend it so that it can come into force only after a confirmation referendum in which options would be to stick to these conditions or stay." According to the polls, I have no doubt that an amendment to obtain a confirmation vote would be successful. "

Pro-referendum MPs are also exploring other options, including reviving the May agreement and submitting it to a second referendum.

Nick Boles, the former Conservative MP who resigned for Brexit, said he would support any agreement accepted by the EU, while stating that, if no agreement was to emerge from the Council of the EU, a second referendum would be necessary. "I have been very reluctant to accept that a referendum may be needed to break the stalemate," he said. "But if Johnson is unable or unwilling to accept an agreement with the EU next week, we will have no alternative. An instant election will not solve anything and could prolong the agony.

"We should instead hold a referendum offering citizens the choice between a flexible agreement on Brexit and keeping in the EU. Parliament should adopt all the laws necessary to implement the agreement. Thus, if people voted again in favor of Leaving, the Brexit would take place immediately and would no longer require a vote in parliament.

Keir Starmer

Keir Starmer says he'll insist on a confirmation vote. Photography: Sean Smith / The Guardian

Paul Masterton, Scottish Conservative MP, said: "My instinct is that the numbers are there for a second referendum if [Johnson] do not bring back an agreement, but they will not do it if it does. "

Keir Starmer, secretary of Brexit's shadow, said Saturday at a conference that, "If Johnson manages to negotiate an agreement … we will insist that it be returned to the people at the same time." 39, a confirmation vote. If he can not – or should I say no, get an agreement … we will take all necessary steps to prevent our country from getting out of the EU without an agreement. "

If Johnson has not signed an agreement before October 19, he is obliged by Benn law to ask the EU for an extension of membership in the UK until January 31st. Starmer said the Labor Party would ensure that he was complying with the law. "I've heard ministers suggest that Johnson could send a second letter to the EU to tell him that he did not want an extension. This is equivalent to attaching a post-it to divorce papers saying "I'm laughing"! It's a ridiculous idea. So let's be clear: if no agreement is reached at this time next week, Boris Johnson must request and accept an extension. "

Johnson is expected to update the practice Sunday afternoon. A source on Downing Street said, "We have always wanted an agreement. It is good to see progress, but we will wait to see if this is a real breakthrough. We are far from a final agreement. Weekends and next week are essential to leave with an agreement on October 31st. We are ready to leave without agreement on October 31st. "