Maryland Gov. Larry Hogan (R). (Patrick Semansky/AP)

The United Association of Plumbers and Pipefitters on Thursday endorsed Gov. Larry Hogan’s bid for reelection, the first time the labor group has backed a Republican gubernatorial candidate in Maryland.

The 345,000-member union, which is based in Annapolis and has nearly 7,000 members in the state, generally supports Democrats — including Barack Obama and Hillary Clinton in their respective presidential campaigns.

But the group endorsed then-New Jersey Gov. Chris Christie (R) when he ran for reelection in 2013 and has “financially supported other pro-labor Republicans,” said Kristin Fleckenstein, the union’s communications director.

In 2014, the union backed then-Lt. Gov. Anthony G. Brown, Maryland’s Democratic gubernatorial nominee, over Hogan.

The decision to back Hogan this year was not controversial and was supported by the “overwhelming majority” of the union’s leadership, Fleckenstein said.

In a statement, the union’s general president, Mark McManus, cited Hogan’s “bipartisan leadership” and said “his inclusive energy policy is not only good for the environment, but will also add good paying jobs to the Maryland economy and support skilled tradesmen and women.”

Seven major Democratic candidates are competing in the June 26 primary to challenge Hogan, who does not have a primary opponent.

The leaders in the crowded field are former NAACP president Benjamin Jealous and Prince George’s County Executive Rushern L. Baker III, but nearly 4 in 10 likely voters have not settled on a candidate, according to a Washington Post-University of Maryland poll .

Hogan, who has a 71 percent job-approval rating among all Marylanders and a significant fundraising advantage over his Democratic challengers, officially kicks off his reelection campaign in Annapolis this weekend.