Jeremy Corbyn, the leader of Britain's opposition Labor Party, announced Monday that his bloc in Parliament would support a second referendum to stop what he called "a damaging Tory Brexit."
While Labor Party activists have been pushing their leader for months to publicly back another public vote on Brexit, Corbyn has been cold to the idea.
He has been wary, in part, because many Labor voters — especially in Wales and the north of England — want Britain to leave the European Union.
Corbyn's support for a second referendum does not mean that another public vote will happen. Prime Minister Theresa May, her government and most of her Conservative Party remain opposed to a do-over.
Nor was it clear on Monday night what kind of second referendum Corbyn supports. Brexit opponents want voters to be given a clear choice of leaving or staying in the European Union.
Others say a second referendum, if it ever took place, should be more limited — asking voters, for example, if they support the deal May has negotiated with the European Union or not.
This week will see lawmakers in Parliament likely putting forward motions seeking to delay Brexit beyond the scheduled departure date of March 29. Other amendments will try to stop Britain from leaving the European Union with no deal — a scenario that could cause economic chaos.
Corbyn said Monday that Labor would also introduce its own amendment, laying out the party’s alternative deal for a much softer Brexit than May has negotiated with the Europeans, and one that would likely keep Britain in an EU customs regime and single market. Such an arrangement would likely mean that Britain would have to continue to accept the free flow of immigrants from Europe.
Corbyn said that only if Parliament and the government reject Labor's vision for Brexit would he and his party rally around a second referendum in order to stop May's deal.
May spent the weekend in the Egyptian resort of Sharm el-Sheikh, at a meeting of the leaders of Europe and Arab states, seeking support for additional language to her Brexit deal that would make it palatable to her own party.
Many Conservative Party lawmakers have rejected May's Brexit deal because it could keep Britain too closely tied to Europe in order to guarantee that there be no return of a hard border in Ireland.
While in Egypt, the British prime minister resisted calls to seek a delay for Brexit.
"A delay in this process doesn't deliver a decision in Parliament, and it doesn't deliver a deal," she said at a news conference Monday. "What it does is precisely what the word ‘delay’ says, it just delays the point in which we come to that decision."
Corbyn's spokesman said the Labor leader believes that May is "recklessly running down the clock" in an attempt to "force MPs to choose between her botched deal and a disastrous no-deal."
Corbyn's move toward backing a second referendum was applauded by Labor leaders who don't like Brexit. David Lammy, a Labor lawmaker who backs a second referendum, tweeted, "This is a big step towards uniting our party and most importantly our country. No Brexit deal meets the fantasy promised in 2016. So the only way any specific form of Brexit can be made legitimate is through ratification in a #PeopleVote which includes the option to remain."