Labour may throw its weight behind moves to hold a second Brexit referendum - but not until next week, a senior frontbencher has claimed.
Shadow foreign secretary Emily Thornberry said she thought it would happen then but admitted 'I don't know for sure'.
She admitted that in the unlikely event Theresa May's Brexit deal had passed last night Labour would have called for a second vote.
In moves that have frustrated a lot of Remain-supporting Labour MPs Jeremy Corbyn has continued to be cool on the idea of a new referendum.
This was despite the party agreeing at its conference last year to seek a referendum if Theresa may refused to agree to their own version of Brexit, or call a general election, both of which she has refused to do.
Shadow foreign secretary Emily Thornberry said 'I don't know for sure, because I just don't - I don't even know what's going to happen today' when asked about when Labour would call for a second referendum
Jeremy Corbyn, pictured today, is expected to whip Labour MPs to vote against a no deal Brexit in the House of Commons tonight
Appearing on the Emma Barnett Show on BBC Radio 5, Ms Thornberry was pressed on when the party would call for a new Brexit vote, saying: 'I suspect it will be next week.
'But I don't know for sure, because I just don't - I don't even know what's going to happen today.'
However she did confirm that a second referendum remained party policy.
'Frankly if we end up in some log jam, then I'm afraid we are going to need to go back to the people and we are going to need to ask them what they want to do next,' she added.
Labour is set to help block a no deal Brexit tonight in another crunch vote in the House of Commons.
Jeremy Corbyn will whip his MPs to vote against a plan that would see the UK crash out of Europe without agreements for future co-operation with Brussels.
It comes after the Labour leader called for no deal to be 'taken off the table' following the defeat of Prime Minister Theresa May's plan last night.
Mr Corbyn wants a General Election and, if successful, would put forward an alternative exit plan that would keep Britain in a customs union with the EU.
If MPs reject no-deal - as most Westminster observers expect - a third vote will follow on Thursday on whether to request an extension of the two-year Article 50 negotiation process, delaying Brexit by a number of months.
It comes after Labour helped block Theresa May's Brexit deal in last night's vote, with the Prime Minister's plan defeated by 149 votes
The Prime Minister's hopes of saving her deal after a last minute dash to Strasbourg late on Tuesday turned to ashes in the Commons last night as the new concessions were hammered by MPs
Labour's support for a second referendum remains unclear, with shadow business secretary Rebecca Long Bailey today saying the party has 'not ruled out' a People's Vote weeks after Mr Corbyn told his MP's he would call for one to 'stop a damaging Tory Brexit'
Ms Long Bailey told BBC Radio 4's Today: 'Now I think it's the opportunity for Parliament to set the agenda and take control because we have a Government now which isn't in control.'
Asked if Labour would push for another motion of no confidence in the Prime Minister she said it was 'something that we may consider in the future'.
Mr Corbyn, pictured at his London home today, wants a General Election to be called and, if successful, would put forward his own plan to keep the UK in a customs union with the EU
Pressed on Labour's position on a second referendum she said: 'We have not ruled out a People's Vote but our priority is securing a deal.'
Labour MPs were previously whipped to oppose a no deal Brexit in January when they helped narrowly pass the Spelman amendment, a non-binding motion calling for the scenario to be ruled out.
Mrs May has given Conservative MPs a free vote tonight, meaning they can vote with their conscience rather than follow the party line.
Mrs May has indicated she will vote against no deal, and with Labour's support it is likely a majority in Parliament will follow suit.
It is expected to be a very different result from last night, when just three Labour MPs - John Mann, Caroline Flint and Kevin Barron - voted for the Government's deal to leave.
Hours before tonight's vote, ministers announced worrying new tariffs that are likely to provoke more accusations of scaremongering after months of apocalyptic warnings about the impact of a no deal Brexit.
Under the no deal plan revealed this morning, 87 per cent of products would be subject to zero tariffs in an effort to stop price spikes and kick-start trade with Britain from across the world.
But ministers said products from the EU including beef, pork, chicken, butter, cheese and fish would also be subject to import taxes expected to push up prices in the supermarkets from March 29 if there is no deal.
Labour's opposition - and the deal's rejection by 75 Brexiteer Tory rebels alongside the DUP - sunk Mrs May's motion last night with Boris Johnson saying Mrs May should put her deal to bed
There were 75 Tory rebels - down from 118 last time - as well as all 10 DUP MPs. Just three Labour MPs backed the deal. The Prime Minister got back about 40 MPs from the January 15 vote
Cars from the EU would be subject to a a 10.6 per tax on the cost of all 'fully finished' vehicles - making the prices of an average vehicle surge by £1,500.
However in a seemingly confusing loophole in no deal plan, Northern Ireland's border would remain open at least 'temporarily' and goods entering from the Republic would not face tariffs to preserve the Good Friday agreement.
The situation will raise fears that the Northern Irish border could become a smuggling route for EU products.
With just 17 days until the UK is scheduled to leave the EU, hardline Eurosceptics sided with Labour last night to inflict a crushing 149-vote defeat on the Prime Minister.
A delay to the March 29 departure date is now almost certain. Mrs May's massive defeat also opens the door to drastic options such as a general election or second referendum.
Speaking in Strasbourg, where the European Parliament is gathering for a debate on Brexit ahead of the next European Council summit, the EU's chief negotiator Michel Barnier said: 'Again the House of Commons says what it doesn't want. Now this impasse can only be solved in the UK.'
Amid speculation about how long she can survive in Downing Street, the Prime Minister's aides insisted she had not considered resigning.
Boris Johnson is among leadership candidates sizing up their chances.