Bernie did show some some official support from a union endorsement poll:

At a meeting of the Utility Workers Union of America in Florida this week, Bernie Sanders won 65 percent of the vote in cell phone poll of the 400 elected delegates to the convention. Clinton won 23 percent, with Martin O’Malley taking 7 percent and the combined Republican field winning 5 percent.

The union is relatively small but still worth noting.

More important:

In a possible setback for Hillary Clinton, the AFL-CIO’s political committee has recommended the nation’s largest labor union federation delay endorsing a candidate for the 2016 presidential race as it seeks to push her to be more supportive of its policies on issues such as trade and wages. The committee on Monday voted unanimously to support the proposal, three union sources told Reuters. The recommendation will be presented at a July 29-30 meeting of the executive council of the federation, which will make the final decision. It could reject the recommendation and still go ahead with an endorsement, though one of the sources said that is unlikely. The move highlights the pressures Clinton is facing to take a tough stand against the Trans-Pacific Partnership, a proposed free trade deal backed by President Barack Obama but vigorously opposed by unions who see it as detrimental to jobs and wages in the U.S. Unions also want her to back labor-friendly policies on other issues, such as the minimum wage and the Federal Reserve.

The federation has been trying to quell a revolt in its ranks as some local unions have declared their support for Sanders, who is known for his progressive stance and who has spoken out strongly against the TPP. In contrast, Clinton has simply said that any final trade agreement needs to include strong worker protections and that she will reserve judgment until a completed deal is presented. Negotiators from the U.S, and 11 other nations from the Pacific Rim, including Japan, Vietnam, Malaysia, Australia, Mexico and Canada, are meeting in the next week in Hawaii in an attempt to reach a final agreement. The trade deal will likely be the top issue at the two-day gathering of the AFL-CIO, which represents workers in a wide range of occupations, from brick layers to machinists to nurses.[emphasis added]

And:Like the rest of the challenges facing Bernie, it's a steep hill to climb to nab the AFL-CIo's endorsement, whatever the merits. But, time, in this case, is his friend.