Labour MPs are to be whipped to support a motion demanding a second referendum on any Brexit deal passed by this Parliament before its ratification.
There was confusion over the party’s stance after frontbencher Barry Gardiner warned Labour would have difficultly backing the plan for a “confirmatory” referendum as it was “not a Remain party”.
A party spokesman said: “In line with our policy, we’re supporting motions to keep options on the table to prevent a bad Tory deal or no deal.”
The decision could make the proposal one of the most widely supported in a series of indicative votes taking place in the House of Commons on Wednesday.
But it risks rebellion among MPs who think Labour should not be seen to be putting obstacles in the way of Brexit.
Labour will also whip its MPs to support the party’s own alternative plan, as well as customs union proposals tabled by MPs Gareth Snell and Kenneth Clarke.
And they will be encouraged to support the “Common Market 2.0” motion tabled by Conservative MP Nick Boles, which sets out proposals for continued participation in the single market and a “comprehensive customs arrangement” with the EU. Leader Jeremy Corbyn himself will vote for this plan, as part of his efforts to find consensus across the House, said a source.
A party source said that decisions on any disciplinary sanctions for MPs breaking the whip in these unusual circumstances would be taken after the event by the opposition whips’ office.
Mr Gardiner’s comments in an early-morning radio interview sparked an angry response from some Labour MPs who said they flew in the face of party policy, while deputy leader Tom Watson said he was in favour of the plan.
The shadow international trade secretary said that supporting the Beckett motion would imply Labour did not accept the result of the 2016 EU referendum.
He said its wording meant that voters could be faced with a choice between accepting Theresa May’s deal – which Labour opposes – or the UK staying in the EU.
“It would be saying we could accept what we have always said is a very bad deal. Therefore it looks as if the attempt to have a public vote on it is simply a way of trying to Remain because nobody likes this deal,” he told the BBC Radio 4 Today programme.
“Therefore, to put that up as the only alternative in a public vote and say ‘we will let it go through’ looks as though you believe that at the end of it Remain would be the result.
“It is not where our policy has been. Our policy is clearly that we would support a public vote to stop no-deal or to stop a bad deal, but not that we would allow a bad deal as long as the public had the opportunity to reject Brexit altogether.
“That implies that you are a Remain party. The Labour Party is not a Remain party now. We have accepted the result of the referendum.”
Labour backbencher Wes Streeting said Mr Gardiner’s comments were the “complete opposite” of what MPs had been told would be happening in the vote.
“The opposite of what Labour stands for. Urgent leadership needed. We live in hope…” he tweeted.
Fellow MP Jess Phillips tweeted: “It is NOT Labour policy only to vote for peoples vote only in circumstances of no deal. NOT AT ALL.”
Speaking before whipping arrangements were agreed, shadow chancellor John McDonnell said Mr Gardiner’s remarks were “exactly in line” with party policy.
“We had to accept in our manifesto respect for the referendum result. We campaigned for Remain, we lost, we have to accept that,” he said.
“What he is saying is exactly in line with party policy. We have got to prevent a new deal, prevent a bad deal, advocate for our own policy, try to get a general election if we can, but failing that, if there is a logjam, yes, we will if necessary go back to the people.”
On Tuesday, shadow foreign secretary Emily Thornberry predicted the motion would be “popular” while the architect of the plan, backbencher Peter Kyle, said he believed Jeremy Corbyn would support it, despite his previous reluctance to back a second referendum.
“He will order MPs to vote for this. We had a really constructive process of engaging with him. At no point was he instinctively against this,” Mr Kyle told the Today programme.