When I first met Brooklyn-born Bernie Sanders, he was a relatively marginal figure in his adopted state of Vermont. It was 1976 and he was running, unsuccessfully and for the fourth time, as a candidate of the Liberty Union Party (LUP).

Liberty Union was a radical third party spearheaded by opponents of the Vietnam War who had, like Sanders, washed up in the Green Mountain State as the sixties subsided. At its historic peak, the LUP garnered maybe 5 or 6 percent of the statewide vote for some of its more presentable candidates — in short, nothing like the winning margins racked up in recent years by the far more savvy and effective Vermont Progressive Party, which now boasts a ten-member legislature delegation and attracts growing union support.

During Sanders’s quixotic mid-1970s bid to become governor of Vermont, I accompanied him to a meeting of local granite cutters, teamsters, and electrical workers. This was not a “flatlander” crowd, nor one dominated by full-time union officials. His audience was native Vermonters, some of them Republican, who were still punching a clock at local quarries, trucking companies, and machine tool factories in an era when the future home state of Ben & Jerry’s and Vermont Teddy Bear Co. still had impressive blue-collar union density.

These local union delegates had come together to make candidate endorsements under the banner of the Vermont Labor Forum, a coalition of unions outside the AFL-CIO. Sanders then delivered what is now known — due to its essential continuity over the last four decades — as “The Speech.” (For one of its longer iterations, see his 2011 book by the same name.)

Sanders’s persuasive message to the Labor Forum was that corporations were too powerful, workers were getting screwed, and both major parties were beholden to “the bosses” (or, as Sanders might call them today, “the billionaire class,” a social category not yet invented forty years ago).

Sanders’s appeal for working-class support in 1976 seemed most persuasive to rank-and-file representatives of the United Electrical Workers (UE). They were, of course, members of a left-led national organization that had long favored political action outside the Democratic Party. However, in deference to their more cautious colleagues, the UE members politely went along with the Labor Forum majority, which, per usual, voted to endorse Vermont Democrats, despite Liberty Union’s superior labor bona fides.

This labor tendency to gravitate toward the least problematic of the two major parties is still with us today. Every election cycle, in every part of the country, AFL-CIO unions and unaffiliated labor organizations make pragmatic calculations about who to back and fund.

Rarely do they take a chance on third-party candidates, no matter how ardent their support for labor causes. Even a union rank-and-filer who runs against a corporate Democrat (for example, Howie Hawkins, the blue-collar Green who challenged incumbent Andrew Cuomo for New York governor last year) finds it hard to collect labor endorsements.

A few union leaders have recently vowed to withhold future support from Democrats who favor President Obama’s Trans-Pacific Partnership deal, but Hillary Clinton will certainly be exempted from any such retribution. By the 2016 general election — and much sooner, in the case of some national unions — organized labor will be in full lesser-evil mode once again.

The only place in the nation next year where union members will have viable, pro-labor third party candidates to support, at least at the state and local level, is Vermont. And for that the US labor movement has Sanders and other Vermont progressives to thank.

When Sanders comes knocking on their door, looking for support in his presidential primary challenge, trade unionists in other states should remember his long history of helping Vermont workers get their act together, in politics, organizing, and contract strikes. It’s a track record that few “friends of labor” can match.

Sanders got his own electoral act together by going local in 1981. Instead of persisting as a fringe candidate in futile statewide races, he joined a four-way contest for mayor of Burlington, Vermont’s largest city. Sanders beat the incumbent, a five-term Democrat, by ten votes.

As mayor, Sanders immediately hired a new human resources director for Burlington. This union-friendly lawyer worked to improve relations between city hall and municipal workers represented by the American Federation of State, County and Municipal Employees (AFSCME) and the International Brotherhood of Electrical Workers (IBEW).

During his four terms, Sanders continued to champion the cause of workers, tenants, the poor, and unemployed, while revitalizing the city. Under the Sanders administration, Burlington backed worker co-ops, affordable housing initiatives, new cultural and youth programs, and development of the city’s waterfront in a way that preserved public access and use.

“We were paying attention to low- and moderate-income neighborhoods rather than just downtown or the big-money interests,” Sanders told the Nation last year. “In fact, I went to war with virtually every part of the ruling class in Burlington during my years as mayor.”

The result, according to Sanders, was that “large numbers of people who previously had not participated in the political process got involved.” In addition, Sanders allies won up to six seats on the city council and campaigned as the Progressive Coalition (the forerunner of the statewide Progressive Party, which was founded in 1999).

But even a left-wing independent with a laudable record of labor advocacy at the municipal level found it hard to attract national union backing when he sought higher office. In 1988 major unions largely ignored Sanders when he ran for Congress against a Democrat and Republican. The latter won, but two years later, Sanders ran again and ousted the GOP incumbent, with more union support this time. Only gradually and very slowly has the country’s longest serving independent in Congress received the kind of national union funding that he should have gotten from the very beginning.

On Capitol Hill, Sanders blazed a trail not followed since Vito Marcantonio served six terms in Congress, between 1939 and 1951, as the lonely tribune of the New York City–based American Labor Party.

Fifty years later, during the Clinton administration, Sanders helped create a left pole for mainstream labor’s soon-to-be-thwarted campaign to reform the National Labor Relations Act. He introduced a “‘Workplace Democracy Act” to comprehensively reform and strengthen workers’ rights . . . to improve living standards for American workers, which have fallen precipitously.”

Sanders also promoted “economic conversion” — refashioning Pentagon-dependent manufacturing firms to produce socially useful goods — a cause since downplayed or abandoned by major industrial unions themselves.

Back in Vermont, Sanders used his congressional office to help workers get better organized, in their workplaces and communities, even when the labor movement lagged behind in both areas. He not only urged Vermonters to vote “yes” in union representation elections, he actually convened annual meetings of local labor activists to assist them in developing more successful organizing and bargaining strategies in the private and public sector. To stimulate new rank-and-file thinking, Sanders and his staff invited out-of-state labor speakers who were part of national efforts to revitalize organized labor.

He has also been a staunch and longtime ally of the Vermont Workers Center, the statewide community-labor coalition that fights for single-payer health care, immigrants’ rights, paid sick leave, and other working-class causes in the Green Mountain State.

When Vermont Verizon workers that I represented opposed the company’s sale of its northern New England landline operations in 2006, Sanders was campaigning for the US Senate seat that he now holds. He convened a public forum highlighting the reasons for our “Stop The Sale” campaign and brokered a meeting with the proposed buyer, FairPoint Communications, that enabled us to confront top managers about the company’s record of anti-unionism.

More recently, as labor opponents of the sale predicted, Verizon’s successor has floundered financially and tried to impose contract concessions on its workforce of several thousand. During their four-month strike last year, FairPoint union members had no stronger political ally, in public and behind the scenes, than Sanders.

Sanders’s four decades of active engagement with workers’ struggles in Vermont has provided a model for the Vermont Progressive Party’s own strong labor orientation. The VPP’s elected steering committee now includes key union activists in Vermont; its public office holders — on the Burlington City Council and in the state legislature — regularly join union members where major party officials are scarce: on picket lines and at rallies and press conferences. Members of my own union and others have been recruited to run as candidates for what has become the country’s most successful state-level third party.

It’s an axiom of labor solidarity that help received, in a period of need, will be reciprocated down the road. Vermont union members learned long ago that the mutual benefit derived from their work with and for Sanders goes far beyond the results of labor’s usual (and sometimes tawdry) transactional relationships with public officeholders.

That’s why trade unionists in Vermont have turned out for Sanders as much as he’s aided them over the years. Let’s hope that their union brothers and sisters in other Democratic primary states will figure out which side they should be on, without the benefit of such long personal association.

It’s promising that many rank-and-file activists have already signed up to join the “Labor Campaign for Bernie.” Last week, the Vermont State Labor Council urged the national AFL-CIO to support Sanders, calling him “the strongest candidate articulating our issues.”

But if the rest of organized labor plays it cautious and safe, jumping on the Clinton bandwagon instead of rallying around Sanders, it will be just one more sign of diminished union capacity for mounting any kind of worker self-defense, on the job or in politics.