Democratic 2020 presidential hopefuls are quickly warming to the idea of allowing their own campaign workers to unionize -- a move that shows the rising influence of labor-aligned activists in the party, and one that could increase campaign costs in the long run.

Sen. Bernie Sanders, I-Vt., campaign team announced Friday that some of their employees have unionized, touting that this makes them “the first major party presidential campaign in history to have a unionized workforce.”

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Most of Bernie 2020’s “bargaining unit employees” recently selected the United Food and Commercial Workers Local 400 to be their “exclusive bargaining representative,” the campaign said. Campaign Manager Faiz Shakir hailed the lawmaker as being “the most pro-union candidate” among the 2020 field and said they’re “honored that his campaign will be the first to have a unionized workforce.”

It's an idea that has caught on among a wide Democratic field seemingly willing to entertain a range of proposals that would have been non-starters in past cycles. While candidates seize on calls to pack the Supreme Court, abolish the Electoral College and end the filibuster, the idea of letting their staffs unionize is tame by comparison.

While Sanders became the first candidate to actually go ahead with unionization, former San Antonio Mayor Julian Castro announced in January that he will pay all campaign workers, including interns, $15 an hour or more. Officials said they would support a union as well if staff chose to organize, according to The San Antonio Current.

Meanwhile, on Tuesday night, former Rep. Beto O’Rourke, D-Texas -- who entered the race last week -- said that if campaign workers want to unionize, he would “support it all the way” as he made a laundry list of promises to potential campaign staff.

"Absolutely, if those who work on this campaign, and who comprise what I hope will be the largest grassroots effort this nation has ever seen, want to unionize, I support that all the way," he told Fox News when asked if he supports unionization.

"In the meantime, I'm going to make sure that we pay among, if not the highest wages, that everyone who works on the campaign is paid a living wage, excellent health care, child care so that everyone can work whatever their conditions are."

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"But if these employees also want to unionize, I absolutely support that," he added.

It remains to be seen what the outcome of such decisions could be, but big campaigns could end up with costlier wage bills, especially if overtime (a common feature on the grueling campaign trail) is also compensated with time-and-a-half, as unions may demand.

The push toward unionization is a sign of the difficult path candidates must walk, as they make calls for increases in the minimum wage, universal health care and other issues -- while pitching other policies that concern labor organizations.

Take the Green New Deal -- a radical overhaul of America’s economy and energy use that almost all 2020 Democrats have backed, and that the AFL-CIO recently warned could cause “immediate harm” to millions of their members.

“We will not accept proposals that could cause immediate harm to millions of our members and their families. We will not stand by and allow threats to our members’ jobs and their families’ standard of living go unanswered,” the union's energy committee said in a letter. “We are ready to discuss these issues in a responsible way, for we all recognize that doing nothing is not an option.”

Campaigns that are not perceived as treating workers well can also see those issues distract from their core message. Sen. Amy Klobuchar, D-Minn., has struggled to move past accusations that she mistreats her staff, with reports that she has thrown binders at staff, torpedoed job opportunities and forced them to clean a comb she used to eat a salad.

Sanders, meanwhile, has been hit by claims that sexual harassment allegations against a staffer on his 2016 campaign were not taken seriously by his campaign managers. He has since apologized and said that "our standards and safeguard were inadequate."

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The unionization push is the latest big idea to be grasped by both lapels by candidates seeking to distinguish themselves from a broad field, and to promote their own progressive street cred.

In recent weeks, top 2020 Democrats have embraced a wealth of ideas that were once out on the fringes of the party -- including the Green New Deal, reparations, packing the Supreme Court with more judges and abolishing the Electoral College.

Fox News' Elizabeth Zwirz contributed to this report.