Theresa May will dash to Berlin tomorrow to persuade European Union leaders to grant a short extension to Article 50 while the government still wrangles with how to progress with Brexit.
Downing Street said that "good-natured" dialogue with Labour had continued through the weekend, following a series of formal meetings last week, with both sides showing a "willingness to co-operate".
In a clear attempt at placating her hard Brexiteer party MPs, May insisted that there are areas where the two main United Kingdom parties, Conservatives and Labour, agree.
"The longer this takes, the greater the risk of the United Kingdom never leaving at all".
Labour wants a customs union with Brussels, something May consistently ruled out as it would prevent Britain striking trade deals with the rest of the world.
May reiterated her warning that Britain may not leave the European Union at all if she can not get a deal through Parliament.
Corbyn has said he was "waiting to see the red lines move" and had not "noticed any great change in the government's position".
Labour is also facing internal division, with 80 MPs writing to Corbyn urging him to secure a guarantee of a second referendum in any deal.
After speaking to May, Mark Rutte, the Dutch prime minister, said: "Crucial to know when and on what basis United Kingdom will ratify the withdrawal agreement".
"If the United Kingdom were to commit to remaining in the customs union, it would make a total and utter nonsense of the referendum result", said the former foreign secretary in his regular column in the Daily Telegraph.
Writing in the Mail on Sunday newspaper, Raab believed striking a deal with Corbyn risked handing the keys of 10 Downing Street to the Labour leader and destroying Brexit in the process. "If we can not secure a majority among Conservative and DUP MPs we have no choice but to reach out across the House of Commons", she added.
Downing Street is understood to have made an offer to enshrine guarantees on workers' rights and environmental protections into United Kingdom law, making it more hard for a new prime minister to undo them.
But Johnson said Britain staying in a customs union, "would make a total and utter nonsense of the referendum result".
Mrs May wants another Brexit extension to June 30 but European leaders have started to spell out the price for agreeing to the delay.
Irish Prime Minister Leo Varadkar said it was "extremely unlikely" a member would veto another extension and revealed he now favoured a lengthy delay.
Talks between Britain's two big political parties resume Monday after Prime Minister Theresa May issued a stark warning that the Brexit people voted for could "slip through our fingers".
If passed, May will have to bring a motion to parliament on Tuesday, pledging to request an extension in Brussels and outlining the length of the planned for delay.