There might be much to criticize about the Biden administration’s embrace of protectionism. Its political logic, however, seems impeccable: to recover the White working class enthralled by Donald Trump’s platform of unabashed protectionist ethnonationalism, the Democratic Party must overcome its image as a cabal of out-of-touch, college-educated cosmopolitans.

It will come as a disappointment, then, that the administration’s efforts to recast the Democrats’ economic platform is not performing according to plan. White voters without a college degree don’t appear to be biting.

Assorted pundits have been stretching to untangle the conundrum. Perhaps workers just need more time to figure out that the Biden administration has improved their lives. Perhaps partisanship has become so entrenched that it shapes Republicans’ grim assessment of the economy. (Maybe metaphysics has something to do with it?)

But there is a more reasonable explanation: Democrats spent half a century building a brand as globalist shills, moving away from the New Deal paradigm that cemented the allegiance of the White working class despite its disagreements with Democratic positions on abortion, race, guns and other issues of “culture.” It will take more than a single administration’s offer to grow the economy “from the middle out and the bottom up” to pull those voters back into the fold.

Ilyana Kuziemko from Princeton, Columbia’s Ebonya Washington, Gavin Wright from Stanford and Jiwon Choi from Brandeis University published a study a few years ago on one of the key episodes in the transition: President Bill Clinton’s break from a quarter-century of Democratic protectionism to launch the North American Free Trade Agreement in 1994, despite outright opposition from organized labor.

The study documented particularly steep job losses starting in the mid-1990s in counties tied to industries exposed to competition from Mexico. Most of these counties had long voted Democratic. By the year 2000, however, they had tilted toward Republicans in House elections.

It’s not all Clinton’s fault, though. Another study by Kuziemko, with Suresh Naidu and Nicolas Longuet-Marx from Columbia, detects the Democratic shift against working-class priorities starting as far back as the Carter administration.

The rise of the New Democrats, they argue, moved the party away from its traditional attachment to unions, job guarantees, minimum wages and protectionist trade policies. The Democratic platform dropped its support for “pre-distribution” — policies designed to improve workers’ lot in the job market — and bought into the notion that the government should let market forces rip and deploy a social safety net to assist the economy’s losers, using taxes and government transfers to redistribute prosperity downward.

College-educated Democrats supported this evolution, well-suited as it was to their role in a tech-heavy globalized economy that rewarded their skills. But the old party base of blue-collar workers without a college education did not. They much prefer policies aimed at protecting good jobs, even if that detracts from the economic efficiency of markets. As the Democratic platform moved against their wishes, they moved to the GOP.

Combing through voter party-identification surveys over the years, the researchers found that in the 1940s every additional year of education was associated with a three-percentage-point decrease in the odds that respondents would identify as Democrats. Today, the relationship is exactly reversed.

Republicans are, of course, no more supportive of unions and guaranteed federal jobs than even the most market-friendly Democrats. But their conservative social agenda scored higher among many less-educated voters — especially White voters — who were not enamored with Democrats’ support for liberal goals such as affirmative action. When Trump in 2016 argued that “NAFTA is the worst trade deal maybe ever signed anywhere, but certainly ever signed in this country,” they knew they had found a new home.

Several dynamics surely contributed to the pro-market shift in the Democratic platform, including the stagflation of the 1970s, which discredited strategies that relied on government intervention in the economy. But the economists underscore the role of Democratic fundraising from the college educated. Critically, they point to reforms that weakened the financial influence within the party of unions — the main political voice of blue-collar workers.

Herein lies perhaps an insurmountable obstacle for President Biden’s campaign to convince White working-class voters that the Democrats are back: He can’t promise that Democrats will stick to the new script.

Biden appears enthusiastic about rekindling the love of organized labor, even at the expense of other priorities Democrats care about. (His “Buy American” policies with their “only with union labor” rider will likely get in the way of other objectives, from combating climate change, to feeding kids through the school lunch program.) He looked credible joining UAW workers on the picket line last year. He seems honestly dedicated to steering the economy in workers’ favor.

What’s more, workers seem to be doing well under Bidenomics. Tariff barriers embraced by his administration might be a poor tool to protect jobs. But policies from the American Rescue Plan to the Inflation Reduction Act have contributed to one of the hottest labor markets in half a century. The surge of inflation in the wake of the covid-19 pandemic is over. Real wages have increased despite higher prices, especially among low-wage workers.

But despite all these gains, all those skeptical White blue-collar workers wouldn’t be wrong to wonder whether the next Democratic president might turn around and, say, push for the Trans-Pacific Partnership. After all, the Obama administration signed on to it.

“The worry,” Columbia’s Naidu told me, “is that Democrats are so captured by the educated that even if they offer this policy mix, they can’t credibly promise to prioritize those groups of voters.” There is little in the Democratic Party “to make believable their promises that they will stay on the workers’ side.”