A leader at the United Electrical Radio and Machine Workers of America (UE) said that the labor group backed Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE’s (I-Vt.) 2020 presidential bid because he has actively taken part in fighting for workers' rights.

“He’s supported many of our labor actions, he’s stood for many of the principles and policies we stand for and he’s walked the walk,” Scott Slawson, who is president of UE Local 506, told Hill.TV on Thursday.

“Even outside of campaigns, he’s been on picket lines and petitioned for American workers, so I think for a union standpoint, it was the right call,” he added.

The comments come just weeks after UE, which represents some 35,000 members nationwide, endorsed Sanders at its national convention in Pittsburgh.

The endorsement marked a win for Sanders, who has long advocated for unions.

Last month, Sanders unveiled his “Workplace Democracy” plan aimed at doubling union membership. The proposal also looks to push for legislation that would ensure that all federal workers have the right to strike, and it would end “at will” employment that allows employers to dismiss workers without warning.

“If we are serious about rebuilding the middle class in America, we have got to rebuild, strengthen and expand the trade union movement in America,” Sanders said in a statement.

Union endorsements are prized among Democratic and Republican candidates alike looking to win support from the groups’ leaders and rank-and-file members.

UE, however, is not a rank-and-file union, meaning that members set the policies and make all the decisions that affect their own local union. So, while the national union has endorsed Sanders, its local unions have yet to make such an endorsement.

Sanders is not the first to receive a union endorsement. The International Association of Fire Fighters backed former Vice President Joe Biden's presidential bid in April, citing his “proven track record” of representing union members and working families.

— Tess Bonn