Speaking on commercial radio in London on Friday, Tom Watson said he would support Prime Minister Theresa May's deal, or a revised deal going through parliament, but only if the public was allowed to vote on it too.
He also said he would take part in Saturday's second People's Vote march. The last such march was the country's second-biggest protest since more than a million people turned out for the 2003 Stop the War demonstration against the invasion of Iraq.
"Brexit is stuck in the parliamentary pipework," Watson wrote on Twitter. "The impasse works for neither Leavers or Remainers. I have come to the reluctant view that the only way to resolve this is for the country to have the final say. Tomorrow I will join the #PutItToThePeople march."
Corbyn in the north
Labour delegates voted overwhelmingly at the September 2018 party conference in favor of a second referendum as an option. Last month, party leader Jeremy Corbyn was reported to have said it would "put forward or support an amendment in favor of a public vote to prevent a damaging Tory Brexit being forced on the country."
However, neither Corbyn nor the shadow chancellor John McDonnell will attend the People's Vote march in London. Corbyn will be in Morecambe, Lancashire, campaigning for local elections scheduled for next May, and McDonnell said he would not be marching.
Tensions have been rising this week, with a number of politicians reporting they had received threats because of the positions they have taken over Brexit. Independent Group MP Anna Soubry discussed on Channel 4 news the abuse she has received: "I can't go home this weekend," she said. "I had a really nasty death threat."
The march has attracted support from across the house and beyond. Former Conservative cabinet minister Michael Heseltine explained via the pages of The Spectator. "The Put it to the People march will give voice to the growing concern in the nation that Brexit is going horribly wrong," he wrote.
"A final defeat for the prime minister's deal should be the signal for MPs from across the political divide to work together to find first the political will and then the time and space to hold a People's Vote."
Scotland voted in favor of remain in the 2016 referendum and First Minister Nicola Sturgeon will also attend the London march: "I'll be proud to speak at the @peoplesvote_uk march tomorrow," she wrote on Twitter. "Scotland voted to remain in 2016 but people across the UK must have the chance to get out of this Brexit mess. Whatever Scotland's future — I hope independent — it is in all of our interests for UK to be in the EU."
A letter from the prime minister
For her part, the prime minister wrote to all MPs on Friday, offering talks with MPs and setting out the options for Brexit following her presentation to the European Council on Thursday. In her occasionally repetitive, and sometimes threatening three-page letter, she said it would be "wrong" to participate in European elections and that revoking Article 50 would be to "betray the result of the referendum."
Should her withdrawal agreement be presented to parliament and fail for a third time, then by April 12, "[the UK] would either leave with no deal or 'indicate a way forward before this date for consideration by the European Council," May wrote.
On Friday there were already reports of motions being tabled in the House of Commons on Monday for a series of indicative votes to be held on Wednesday, to whittle down options for a Brexit decision which would gain the support of a majority in the house.
jm/aw (Reuters, AP)