by Stephen Castle

FFORESTFACH, Wales — In a 2016 referendum, Stephanie Holtom voted to leave the European Union, worried about immigration and convinced that other countries were telling the British government what to do.

But outside a supermarket recently in a large, suburban strip mall not far from the Welsh city of Swansea, Holtom conceded she might have been wrong.

“I agreed to come out of Europe, but I am beginning to have second thoughts. I think it’s a mess, and I’m sick to death of it,” said Holtom, who is retired, as she collected her shopping cart. She added that, if there were a second referendum, “people would vote to stay.”

Since a majority of Britons voted narrowly to leave the bloc more than 18 months ago, most politicians have treated a withdrawal, known as Brexit, as inviolable. Even amid signs of a slowing economy, few saw signs of a shift in public opinion.

Until now.

London may be almost 200 miles away, but people here in Wales have noticed that Prime Minister Theresa May is struggling to negotiate Britain’s departure from the bloc, and to control her bitterly divided Cabinet. “I think Theresa May is absolutely hopeless,” Holtom said.

As the political stalemate drags on, and with business leaders issuing ever more urgent alarms about the threats to the economy, growing public doubts are beginning to register in some opinion polls. And opponents of Brexit are quietly cultivating what they see as that rising sentiment in their campaign to soften, if not reverse, the whole process.

They even picked up support from an unexpected quarter when Nigel Farage, the former UK Independence Party leader and the leading proponent of Brexit, recently suggested there might be a second referendum.

Prominent “leavers,” as supporters of Brexit are known, dismiss that possibility, but it may not be as far-fetched as they would have people believe.

Some time later this year Parliament is likely to face a fateful vote on the actual terms of any agreement May can reach with the European Union on Britain’s withdrawal. A defeat in Parliament would prompt a political crisis, very likely topple May and possibly prompt a general election. Potentially, that could open the way to a rethink, to new Brexit options, or to a second referendum.

That is what people like the local Swansea lawmaker Geraint Davies, from the opposition Labour Party, are banking on. He believes the tide is turning against Brexit in Wales, where a majority opted to quit, although Wales is a big recipient of European development aid, and has several industries that might lose from Brexit.

“What I am sensing is that people who voted Brexit in good faith are now saying, ‘Hold on, that’s not what I voted for, and I want a final say,'” Davies said, listing promises made during the 2016 referendum, including one — later ruled misleading by the country’s statistics authority — that quitting would free up 350 million pounds a week, or about $486 million, for health spending.

“You should have the right to look again, and say: ‘You ordered a steak and you ended up with a bit of chewed up bacon. Do you want to accept that?'” Davies added, arguing that Britain faces higher inflation and slower growth, and that, far from getting money back, it has offered around 39 billion pounds, or about $54 billion, in divorce payments to the European Union.

Davies and others have also pounced on recent reports that areas in Wales and central and northern England that voted most strongly for Brexit are set to suffer the greatest economic harm from the rupture.

Experts say they have detected a subtle shift, in Wales and elsewhere. Though few people admit to changing their views, there is growing support for a vote on the terms of any Brexit deal, according to Roger Awan-Scully, a professor of political science in the Wales Governance Center at Cardiff University.

“There is some change on whether there should be another referendum on the issue,” he said. “We have seen a move towards the idea of the public having a greater say.”

Hard-line supporters (and opponents) of Brexit remain steadfast in their views, but many of the less committed have yet to fully focus on what it will mean and have been turned off by the stream of complex, sometimes contradictory, reports emerging from the tortuous negotiations. “It’s a bit like the O.J. Simpson trial: It keeps going on and on and people tune out of it,” Awan-Scully added.

And with signs that public opinion is volatile and could be shifting, the political ice is starting to crack.

When Tony Blair, a former prime minister, called last month for another plebiscite, Brexit supporters derided him as a pillar of a failed, elitist, pro-European establishment.

But it was hard to say the same when Farage suggested there should be another vote. Though Farage appeared later to retreat on the idea, Arron Banks, a big financial supporter of one of the Leave campaigns, endorsed it as well. For hard-line leave supporters, a referendum is a chance to once and for all kill off the argument to stay, and precipitate a clean break with the bloc.

Pro-Europeans, by contrast, would like a plebiscite on the specific terms of any deal negotiated by May’s government, with the option to remain in the bloc if voters prefer.

Several things would have to happen to make that a reality, including a change of government policy and, almost certainly, of prime minister.

Some say it is too late to rethink the withdrawal, given that Britain has invoked its two-year exit clause. Others say that to date the shift in British public opinion, if any, is simply not big enough, and that Brexit support remains strong outside the big cities and in many working-class communities.

But the logic of having a second referendum is compelling. The 2016 vote was a choice between leave and remain, yet was silent on the path that Britain should take thereafter.

At the two extremes, these are starkly different prospects. A soft Brexit could keep Britain integrated within the European Union’s economic model and part of its single market and customs union, accepting all its rules, albeit without having a say over them.

A hard Brexit might cut most of those ties, and take the country toward a low regulation, low tax economy — “Europe’s Singapore” — for example.

The problem is that there is no specific democratic mandate for either option, or even for May’s preferred (though probably unobtainable) idea of something in between. So any outcome is likely to be contested for years to come.

Within May’s government, the implications of Brexit are causing concern, even as hard-line Brexit supporters step up their campaign for a clean break from the bloc.

Following the leak of a government analysis that predicted the British economy would suffer under all of the most likely scenarios, one minister, Phillip Lee, wrote on Twitter that, if the figures were anywhere near right, “there would be a serious question over whether a government could legitimately lead a country along a path that the evidence and rational consideration indicate would be damaging.”

One obstacle to another referendum is the Labour leader, Jeremy Corbyn, a lifelong Euroskeptic, who rejects the idea — despite arguing that, unlike May, he would negotiate a withdrawal that would protect British jobs.

Yet, if May reaches a Brexit deal that takes Britain out of the bloc’s economic structures, Corbyn would face overwhelming pressure to oppose it, a move that, if successful, could bring down the government.

Davies argues that the Labour Party’s large number of youthful members — the bedrock of Corbyn’s support — are strongly pro-European and want a second referendum.

Calls for a reconsideration of Brexit have come not only from Labour’s centrist lawmakers, but from some of Corbyn’s allies on the left, like Paul Flynn, a leading Labour member of Parliament from Wales.

“Isn’t it time to rethink this whole nonsense and plan for a second referendum where the nation comes to its senses?” Flynn recently asked at a parliamentary committee hearing.