Prime Minister Theresa May has insisted she had to reach out to Labour in a bid to deliver Brexit or risk letting it “slip through our fingers”.
The PM said there was a “stark choice” of either leaving the European Union with a deal or not leaving at all.
And shadow business secretary Rebecca Long-Bailey says if no-deal became an option Labour would consider “very, very strongly” voting to cancel Brexit.
Some Tories have criticised the PM for seeking Labour’s help on her deal.
Commons Leader Andrea Leadsom said the Tories were working with Labour “through gritted teeth”, adding that no deal would be better than cancelling Brexit.
MPs have rejected Mrs May’s Brexit plan three times and last week’s talks between the two parties were aimed at trying to find a proposal which could break the deadlock in the Commons before an emergency EU summit on Wednesday.
However, the three days of meetings stalled without agreement on Friday.
In a video message posted on Sunday, Mrs May said she could not see MPs accepting her deal “as things stand”.