Rep.  Donna F. Edwards (D-Md.) has won support from the Washington area Teamsters for her Maryland Senate campaign, two months after her primary rival U.S. Rep. Chris Van Hollen (D-Md.) scored the first union endorsement in the contest.

Van Hollen won support in April from the Baltimore-based Maryland Teamsters in what is turning into a battle with Edwards for the state's organized labor vote in the contest to fill retiring Sen. Barbara Mikulski's (D-Md.) seat in 2016.

The Teamsters Local #639, which represents about 8,500 workers in Maryland, Virginia and the District and is largest in the region, announced their decision Wednesday and became the first labor organization to publicly back Edwards.

Union president Tommy Ratliff said Edwards' record is one that "supports working people. ... I don't think the people of Maryland can go wrong in supporting her."

The congresswoman has enjoyed strong union support in past elections, including the 2008 race that catapulted her to federal office after Edwards unseated an incumbent Democrat. National labor groups have yet to weigh in on the competition but both candidates are racing to lock up support across the state and nation quickly.

The union endorsement comes the same week Edwards announced support from three Charles County elected leaders and a national progressive organization, Women’s Action for New Direction -- one of seven national liberal groups supporting the congresswoman's candidacy. She also has won backing from the majority of council members in Prince George's County where Edwards lives and is part of the Fourth Congressional district she represents.

Meanwhile, Van Hollen boasts support in the Democratic stronghold of Montgomery County and parts of Prince George's County that were previously a part of the Eighth Congressional district. County executives in both counties endorsed Van Hollen.