Joe Biden likes to think of himself as the “most pro-union president” in U.S. history. As his time in the White House winds down and his legacy begins to take shape, there’s no doubt that he has a strong case to make for himself.

Biden, sometimes called Union Joe, has spoken unabashedly about the value of collective bargaining throughout his one term as president. He’s stacked labor agencies with pro-union appointees who are making it easier for workers to organize. He’s openly scolded employers for trying to prevent their workers from forming unions. And he’s even stood alongside striking autoworkers on a picket line — a first for a sitting president.

Yet union membership is hovering near a historic low following a decades-long decline, with barely 1 in 10 workers belonging to a union. There’s little evidence that Biden’s pro-labor policies and bully pulpit have revitalized the labor movement, at least not yet. And much of his union-friendly imprint, shaped as it was without the cooperation of Congress, could be erased by another Donald Trump presidency.

That’s not to mention the record Franklin D. Roosevelt, whose New Deal created bedrock labor standards and paved the way for a massive unionization wave.

So HuffPost put a simple question to several historians who’ve studied the labor movement in the U.S.: Is Biden really the most pro-union president ever?

Some of their answers, written via email, have been edited for length.

Joseph McCartin, Georgetown University:

Biden has a very legitimate claim to being the most pro-union president in U.S. history. Arguably Franklin Roosevelt was able to accomplish more for and in partnership with unions in his New Deal, signing the Wagner Act, Social Security, the Fair Labor Standards Act, and more. But Roosevelt had a more favorable political climate and huge Democratic margins to work with. Given the narrow margins and the polarized environment he had to work with, Biden may go down in history as a miracle worker for what he was able to accomplish. Like FDR, he has altered the relationship between the Democratic party and the unions. If Roosevelt made unions central to the New Deal coalition, Biden has made them a cornerstone of a post-neoliberal Democratic coalition. After years of seeing labor’s concerns overlooked by national Democrats, this has been quite a significant development and one that I believe will outlive Biden just as labor’s alliance with New Deal outlived FDR.

Eileen Boris, University of California, Santa Barbara:

Joe Biden was the first president to walk a picket line in support of striking workers, but by the criteria of the most consequential legislation for worker organizing, no one beats Franklin Delano Roosevelt, whose New Deal saw the National Labor Relations Act that codified the right to organize as well as social insurance (Social Security and unemployment insurance) and labor standards (minimum wages, maximum hours, limits on child labor) – even if the initial acts excluded the predominantly African-American and Mexican-American workforce of agricultural and domestic workers.

Vice-President Kamala Harris, who as a Senator co-sponsored the federal Domestic Worker Bill of Rights, could surpass his legacy if she can push through the care infrastructure (access to child and home care, better working conditions for the care economy) that the Biden-Harris administration lacked the votes to pass, that the increased labor force participation of women and an aging society demands.

Gabriel Winant, University of Chicago:

The Biden administration distinguished itself with the most pro-union presidential posture seen in decades, a reaction to Trump’s strength with blue-collar voters. But this is a low bar to clear, and in any case Biden likely squandered the moment with his contempt for the political left, expressed most clearly around resistance to the genocide in Gaza. Biden rightly recognized that the threat from the far right can only be defeated through tempering neoliberalism, but foolishly tried to selectively pick and choose how to approach this task – continuing policies of recent years in too many areas, and imagining that a fairer economy could be achieved while leaving much of American society unchanged around it. The consequence is that his administration was not able to present a coherent alternative vision of American society or the American economy, only a kluge of threadbare cliches and encouraging statistics.

Nelson Lichtenstein, University of California, Santa Barbara:

Pro-union sentiment is one thing; solid governmental policy transformation is quite another. Joe Biden is undoubtedly in favor of unions and he famously became the first sitting president to actually walk a picket line to demonstrate that. More important, he appointed an activist NLRB [National Labor Relations Board] and marbled his administration with other pro-union figures. So the sentiment is there, but that is not enough to revive the union movement or allow us to call Biden the most pro-union president ever. That prize goes to Franklin Roosevelt, whose pro-union sentiments were often a bit mixed, but whose actual legislative and administrative accomplishments with regard to unionism worked a near revolution, both in the Depression itself and in World War II. Like Biden, FDR broke some strikes, and unlike Biden, he shifted the NLRB a bit to the right toward the end of his second term, but all that pales in comparison to the larger governmental and ideological structures he put in place, a politics that put unionism at the heart of what historians now call the “New Deal Order,” lasting from 1933 to at least 1981.

Tejasvi Nagaraja, Cornell University:

Biden may be the most interesting labor-friendly president alongside FDR. Though less durable than the New Deal, Biden passed policies which facilitate unionization, and has had a remarkably progressive NLRB. He has spoken in support of specific union campaigns, walked a picket line, and has avoided scolding any union campaigns – three labor-friendly merits which FDR cannot claim. Yet both FDR and Biden will be evaluated later by how their labor policies interacted with other issues such as race and war. FDR made compromises with Jim Crow, which ultimately helped undercut universal labor solidarity. Biden will be judged later by his immigration policies. In addition, Biden’s Mideast policies have put him into tension with the very same intergenerational unions that have led a union upsurge in the 2020s.

Jeff Schuhrke, Empire State University:

It’s fair to say Biden has made an earnest effort to be the most union-friendly president, with the glaring exceptions of his role in preempting the would-be railroad strike in 2022 and his more recent refusal to listen to the unions demanding he halt military aid to Israel. But it’s important to remember that “most pro-union president in U.S. history” is a pathetically low bar. Most US presidents have firmly sided with bosses, if they weren’t bosses themselves. Several have ordered federal troops to violently crush strikes or invoked the Taft-Hartley Act to shut strikes down. Twelve presidents (one in four) were literally slave owners. Hopefully Biden has raised that low bar, but what I think matters most for unions is that they use their collective strength to make future presidents see that being unapologetically pro-labor is politically advantageous.

Annelise Orleck, Dartmouth College:

The bully pulpit matters. Biden’s unalloyed enthusiasm for unions and repeated statements that unions are bedrock of the American middle class have supported both the upsurge in labor activism and a sea change in public opinion so that more Americans support unions now than at any time since the 1960s. Symbolism may only go so far, but he has concrete achievements as well. He raised the minimum wage for federal contract employees to $15 an hour and appointed robustly pro-union Secretaries of Labor. Jennifer Abruzzo, Biden’s NLRB chief, vigorously defended workers’ rights to unionize and collectively bargain. And his signature legislation – the Infrastructure Investment and Jobs Act, Inflation Reduction Act and the Chips and Science Act – created millions of good new jobs with rights to collective bargaining and fair-wage standards. Overall, I would agree with his campaign promise. He has been the most pro-labor president since FDR.