Jeremy Corbyn says Labour will back another EU referendum after his alternative Brexit plan was again defeated in the Commons.
But the Labour leader said he will also continue to push for “other available options” including a general election.
John McDonnell said the party would table an amendment for a referendum when the “meaningful vote” on Theresa May’s deal returns to Parliament.
The shadow chancellor also told ITV’s Peston show he would vote for remain.
It came as MPs voted to endorse Theresa May’s Brexit strategy – but only after she made a series of concessions.
The PM also faced a Brexiteer rebellion, after 20 Tory MPs voted against proposals, backed by the government, to delay the UK’s 29 March departure date if there is a no-deal scenario.
But Conservative MP Jacob Rees-Mogg, who was not among the 20 Tory rebels, offered an olive branch to Mrs May, as she continues to seek concessions from the EU on the controversial Irish backstop clause.
“I really do not mind what form of words the Attorney General and the EU agree on regarding the backstop – as long as it expires before the next election and has the same legal status as the deal.”
Other leading figures in the ERG, including deputy chairman Steve Baker, have previously dismissed the legal annex to Mrs May’s agreement being negotiated by Attorney General Geoffrey Cox.
Labour’s Brexit proposals – which would see the UK join an EU customs union – were defeated by 323 votes to 240, a bigger margin than the last time MPs voted on them.
Mr Corbyn confirmed to MPs on Monday he would back another public vote if such a defeat took place after resisting calls to do so from pro-EU Labour MPs.
Conservative Party chairman Brandon Lewis accused Jeremy Corbyn of being “happy to ignore the biggest democratic vote in our nation’s history” by saying he would back another referendum.
BBC News contributed to this article