Jeremy Corbyn, the leader of the UK’s Labour Party, is the most authentically left-wing politician currently leading a major party in the industrialized world. He is also presiding over that party’s historic political collapse.

Labour lags 12.5 points behind the ruling Conservatives in BritainElect’s polling average — significantly worse than Labour’s results in the 2010 election, when it lost power amid the Great Recession. A January 3 YouGov poll found that Prime Minister Theresa May had higher approval ratings than Corbyn among Labour voters.

Team Corbyn, as a result, has decided to make a change — by being even more aggressively left-wing. His team told reporters on Monday that they planned to adopt a new populist media strategy inspired, they said explicitly, by Donald Trump.

In the past 24 hours or so, we began to see the first fruits of this strategy. Early on Tuesday morning, Corbyn said he supported a maximum wage in an interview — and then immediately backtracked on the idea in a high-profile speech to Labour members. In that same speech, Corbyn reversed his prior commitment to freedom of movement and relatively open borders, announcing that Labour would be open to new restrictions on migration from European Union countries. It was a day of flip-flops piled on flip-flops.

In theory, these steps are supposed to tap into anti-elite sentiment fueling the rise of Trump and other right-wing populists. In practice, they’re a disaster — simultaneously proposing bad, unpopular policies and selling out his base on the key issue of immigration.

The maximum wage mess

Corbyn’s maximum wage idea wasn’t spelled out in any policy proposal. It was something he floated, kind of offhandedly, in an interview with the BBC’s Radio 4.

Host John Humphrys asked him whether he would “seek to put restriction on how much they — the fat cats [in finance] — earn.” Corbyn’s answer: “I would like to see some kind of high-earnings cap, quite honestly.” He did not get any more specific on questions like how much he would like to cap — though he did say, as the Guardian archly noted, that it would be “somewhat higher” than the roughly £138,000 ($168,000 US) he makes annually.

This policy proposal was, apparently, not planned. "It's absolutely fucking bonkers,” an anonymous Labour official told the BBC’s Shelley Phelps. “He came up with it off the top of his head.”

The outcry from UK economists and policy experts was pretty much immediate. “It's a totally idiotic, unworkable idea,” Danny Blanchflower, a Dartmouth professor who used to serve on Corbyn’s economic advisory council, tweeted. “Interesting that we haven't heard from any UK Labour MPs or a single economist who think that @jeremycorbyn idea of a pay cap is a good plan.”

There are good reasons even economists who want to hike taxes on rich bankers, like Blanchflower, are so alarmed. If people don’t get to keep any income past a certain point, then they have literally zero reason to continue working once they start making that much money. The result is that companies would shift a lot of business out of the UK, and some people would just stop working, depriving the UK of vital economic activity and raising almost nothing in income.

You could accomplish a lot more by raising marginal taxes on the rich to some higher point and still allowing the rich to keep some money. Thomas Piketty, no neoliberal squish, thinks 83 percent is the absolute highest marginal rate the UK could productively impose on the top 1 percent.

“It's absolutely fucking bonkers”

“You don't raise any more revenue, and you just cause people to, forget about people moving, you get into a situation where people just stop their activities at some point,” left-wing economist Michael Ettlinger told my colleague Dylan Matthews in a 2012 examination of the maximum income published by the Washington Post. “Call me about something more serious some time.”

You might forgive Corbyn on policy if the maximum income were a political winner. But polling suggests it’s not. After Corbyn originally raised the idea in 2015, YouGov polled British citizens on whether they’d support a maximum income of £1 million a year. The result: 39 percent for, 44 percent against.

After all the hue and cry, Corbyn appeared in Peterborough to give his major speech to the Labour faithful outlining his policy agenda for the coming years. He proposed a number of measures for tackling inequality, but pointedly did not mention a maximum income.

When ITV’s Robert Peston asked him about the omission after the speech, Corbyn backed away from a maximum income, saying he preferred policies that would create a maximum ratio (of 20-1) between what executives and the lowest-paid workers at a given company make.

“You could set a limit on top pay. I think it’s probably better to look at the ratio issue,” he said.

Within a single day, then, Corbyn proposed a major policy shift, apparently surprising even members of his own party. That policy was a loser both substantively and politically. Then he left that idea out of the prepared text of a major speech, and ultimately seemed to disavow it.

It’s a complete muddle — and hardly a promising start to the new era of left-wing populism.

Meanwhile, Corbyn sold out the left on immigration

While the fracas over the maximum income consumed most of the British press, Corbyn did something else in his Peterborough speech that sparked controversy — reverse several of his past immigration proposals.

In the past, Corbyn had supported maintaining open borders with the EU even after the UK departs the European Union. In Peterborough, he said he’s no longer committed to that idea.

“Labour is not wedded to freedom of movement for EU citizens as a point of principle,” he said. He then proposed a series of policies that he said would reduce the number of immigrants coming to the UK:

Taking action against undercutting of pay and conditions, closing down cheap labour loopholes, banning exclusive advertising of jobs abroad and strengthening workplace protections would have the effect of reducing numbers of EU migrant workers in the most deregulated sectors, regardless of the final Brexit deal.

Corbyn, here, is arguing that measures to increase immigration numbers, at least in certain sectors, are a threat to economic egalitarianism — that foreign workers are undercutting native-born Britons. This left-wing reasoning is leading Corbyn to work toward a right-wing goal: reducing immigration levels to the UK.

“I see Jeremy Corbyn's new radical populist approach involves mainly agreeing with the Conservatives on ... immigration,” writes Sathnam Sanghera, a columnist for the Times of London.

There’s a kind of logic to this. Anxiety about immigration was the key reason for the Brexit vote’s stunning success, especially with traditional Labour voters in the UK’s post-industrial north. Right-wing populist parties are on the rise throughout Europe due their ability to exploit fears about cultural change caused by immigration.

It’s easy to conclude, looking at this landscape, that any successful populism requires some kind of support for immigration restrictionism. Prominent Labour members — particularly those on the party’s right flank — have been urging Corbyn to tack right on immigration for months. And coupling immigration restrictionism with strong support for the welfare state, an approach called “welfare chauvinism,” has worked pretty well for some European far-right parties.

Experts on populism, though, are dubious that it can work for the left.

“Within Labour, there’s [some support for] a kind of nativism-lite — where you say immigration is problematic, but it’s not as bad as the far right says. That is a nonstarter,” Cas Mudde, a political scientist at the University of Georgia, told me in a conversation two months before Corbyn’s announcement.

The issue, Mudde explains, is that British voters aren’t idiots. They know that Conservative and UK Independence Party leaders have long records of opposition to immigration, and that these parties support much stronger controls on migration than Corbyn does. “Nativism-lite,” as Mudde terms it, serves only to alienate the progressive, urban voters the party needs in any national election.

“People that really have nativist [beliefs] are not going to believe that you really mean it this time,” he says. “They’re going to say, ‘You stop there, but the other party will go even further.’”

Kai Arzheimer, a scholar at Germany’s University of Mainz who studies voting in Western countries, agrees.

“I can’t really believe that it is possible to beat the populists in terms of populism,” Arzheimer told me in an interview. “People realize that it’s a copy.”

Maybe these experts are wrong, and this new tack on immigration will pay off for Corbyn. But it is, at best, a gamble. And, as a substantive matter, it is most definitely selling out immigrants and their left-liberal supporters — who now have exactly no one backing them at the top levels of British politics.