In what could be the biggest blow yet for her campaign, the leader of the America’s largest federation of unions (counting 12 million active and retired “everyday Americans”) has chosen not to endorse Hillary Clinton over Bernie Sanders.

Clinton has racked up endorsements from 18 unions, according to The Hill, including the Service Employees International Union and the National Education Association, while Sanders has garnered just three union endorsements.

Many of these unions have expressed support for the labor policies touted by Sanders, but believe Clinton is more electable.

But, in a relative win for the Sanders’ campaign, according to Huffington Post, the American Federation of Labor and Congress of Industrial Organizations (AFL–CIO) – the largest federation of unions in the United States,  made up of fifty-six national and international unions, together representing more than 12 million active and retired workers – will not be endorsing Hillary…

Richard Trumka – the president of the AFL-CIO – told members of the executive council that the body won’t be holding a vote on whether to endorse Democratic presidential candidates Hillary Clinton or Bernie Sanders at its annual winter meeting in San Diego.

“Following recent discussion at the AFL-CIO’s Executive Committee meeting and subsequent conversations with many of you, I have concluded that there is broad consensus for the AFL-CIO to remain neutral in the presidential primaries for the time being and refrain from endorsing any candidate at this moment,” Trumka said.

The decision is a coup for Sanders’ backers within organized labor. Clinton has managed to lock down endorsements from unions representing a majority of unionized workers in this country. But the AFL-CIO endorsement is the most potent of all, and it won’t be going to Clinton — at least, not yet.

Under AFL-CIO procedures, an endorsement by the executive council needs to be ratified by leaders of the federation’s member unions. It’s likely that Clinton doesn’t yet have the required votes for an endorsement to be ratified.

In his email to members, Trumka said the council would “continue its ongoing discussion” about the 2016 campaign, and thus we suspect this is merely a stalling tactic as quid-pro-quo negotiations are undertaken. Although, given the trend in her numbers…

And this…

“We’re extremely happy” about the decision, said RoseAnn DeMoro, executive director of National Nurses United, a union that has broken away from many other labor groups and endorsed Sanders.

Anything is possible in this election season.