Around a conference table inside the large Washington headquarters of the AFL-CIO, a furious exchange occurred between labor union presidents. It was late February and up for decision by the Executive Council was whether the country’s principal labor federation was going to make a primary season endorsement of Hillary Clinton as favored by the leaders of the largest unions.

According to insiders, tempers flared when smaller unions challenged the Hillary-endorsing big unions such as AFSCME (public employees), the American Federation of Teachers, the National Education Association, the Service Employees (SEIU) and the Food and Commercial Workers (UFCW). These large unions came out for Clinton in late 2015 and early 2016 before they sensed the growing rank and file workers’ preference for the lifetime advocate for workers and union backer, Bernie Sanders.

Listening to the nurses union head speak out for Sanders’ strong pro-labor history, Lee Saunders, president of AFSCME, interrupted her, exclaiming: “I will not allow you to do a commercial for Sanders.” She retorted, “You mean for the only candidate who has a 100% labor record?”

A union leader of postal workers charged the unions backing Hillary as being “completely out of touch with their workers.” AFL-CIO President Richard Trumka then cut off their microphones.

All over the country, the observation by the postal workers’ leader rings true. Even as Lee Saunders read the names of the Democratic presidential contenders at a large Washington state AFSCME membership meeting last October, “only Sanders’ name brought loud, sustained applause,” according to Bloomberg News.

Few union leaders allow a worker referendum to make the endorsement decisions. The 700,000-member Communications Workers of America (CWA) does, and the result was a “decisive endorsement of Sanders,” reported Rafael Navar, the union’s political director. Whether it is the level of enthusiasm, campaigning to get out the vote or talking up their candidate’s record on such issues as minimum wage increases, abolition of public university and college tuition, full Medicare for all (single-payer system) and credibility in standing up to Wall Street, Hillary’s votes and statements do not come close to respecting the working families of America compared to Bernie’s consistent 30-year record.

Based entirely on her lawless record as a pro-war Senator (Iraq), as a war-making Secretary of State (Libya), and her $5,000-a-minute speeches before closed-door, big-business gatherings (in addition to millions in big-money campaign contributions), Clinton will continue to be the sponsor of War and Wall Street.

The volunteer Labor for Bernie grassroots drive is not just growing rapidly but cutting across all union categories and gaining support with non-union workers. There is a potentially massive pool of American workers supporting Senator Sanders as he wins primary after primary, leading up to the April 19th contest in New York - the adopted state base for the Clintons, who are backed by all their monied interests.

This unaffiliated labor awakening bears watching, especially by the long-entrenched, affluent big union leaders. First, Labor for Bernie is fomenting defections by local unions defying their Hillary-endorsing national organizations. So far, over 80 of these union locals have endorsed Bernie Sanders.

Typical of this exodus is Northern California Food and Commercial Workers Local 5, whose executive board voted 30 to 2 for Sanders, reflecting the views of most of its 28,000 members. Local 5’s Mike Henneberry said “For us it was not a very difficult decision. Compare an individual who’s been supporting workers since he was mayor of Burlington [Vermont] with someone who’s been on the Board of Walmart.”

The Service Employees Local 1984 (SEIU), New Hampshire’s largest public sector union, disagreed with its national union and came out for Sanders in November.

The big union leaders don’t smell revolt yet, but they must be worried. If the Clintons continue to play dirty tricks, with the big unions, as was suspected in Iowa and Nevada against the Sanders campaign, the seeds of challenges within the ranks of these unions will be planted. Should Hillary become president and come out for anti-worker trade treaties, return to her former coolness on a living wage and other labor issues and cater to Wall Street, the insurrection could congeal against the big unions who will have taken credit, of course, for her victory, without having delivered a mandate for a labor agenda.

It is the AFL-CIO’s practice of endorsing Democrats without demanding before and insisting after the election that candidates champion ‘card check’, revision of trade treaties, repeal of anti-union labor laws and stronger job safety regulation. The Democratic Party treats the mostly shrinking labor unions as having nowhere else to go. And most union leaders meekly oblige by their chronic submissiveness.

The man to watch is strategist and former labor union insider Larry Cohen. He was for many years the president of the Communications Workers of America (CWA) that has endorsed Sanders. He’s going all over the country helping the Sanders campaign, urging major labor unions, still undecided, like the Steel, Auto, Firefighters and Electrical Workers (IBEW) to come out for Bernie.

But Mr. Cohen is looking beyond the elections to take the energy from the Sanders campaign and politically mobilize tens of millions of non-unionized workers behind a new Congress furthering a new economy as if workers mattered.

Time is of the essence. When will workers again have such a scandal-free, consistent labor champion as Bernie Sanders seriously going for the Presidency inside the Democratic Party? Had Sanders had two more months without this big union opposition, his current momentum could have allowed him to overtake Clinton by now.

Facing a possible four or eight years of the corporatist and militarist Clinton, coupled with U.S. multinational corporations exporting whole industries, not to mention accelerating labor-replacing automation, the hurdles for Americans believing in democracy, justice and peace becomes far, far greater.

So the time for preventive civic and worker engagement with all electoral contests is now!