AUGUSTA — All five Democratic primary candidates for governor have promised not to buy any campaign advertising on WGME-13, Portland’s CBS affiliate.

About 40 union engineers and technicians have been working at the station since February without a negotiated contract, according to Matthew Beck, an IBEW organizer and former station employee.

“We’re accusing them of bargaining in bad faith,” Beck said. “We think they’re trying to bust the union.”

The boycott, called for by Manchester-based IBEW Local 1837, will likely cost the station tens of thousands of dollars between now and June, the union claims.

“The Maine Democratic Party is proud to support the workers of IBEW Local 1837 and applauds all of our gubernatorial primary candidates in supporting this cause,” Maine Democratic Party Executive Director Mary-Erin Casale said, according to the IBEW press release and an e-mail from another party staff member. “We encourage all parties involved to reach a fair collective bargaining agreement as soon as possible.”

The station’s parent corporation, Maryland-based Sinclair Broadcast Group, Inc., says its broadcasts reach 22 percent of U.S. homes with televisions.

The corporation, according to its website, is “one of the largest and most diversified television broadcasting companies in the country today,” with direct ownership or connections to 58 stations in 35 markets throughout the country. The majority of the corporation’s affiliates are with the Fox network owned by Rupert Murdoch.

MaineToday Media has a content sharing partnership with WGME, which was purchased by Sinclair in 2000.

A public relations employee for Sinclair returned a phone call to confirm the corporation owns WGME. Other executives, including Tom Humpage, the general manager of WGME, declined comment.