WASHINGTON — Hillary Rodham Clinton will travel to Massachusetts Thursday, but her day in the Bay State will begin with a downer because the state’s teachers union plans to vote against endorsing her on that occasion as she had hoped.

Making such an early endorsement “does not allow members to be active participants in the kinds of discussion and debate that are central to a democratic union,” Massachusetts Teachers Association president Barbara Madeloni wrote on the union’s Web site.

The National Teachers Association was pushing for the endorsement, Madeloni said.

But she noted that the “tone” at a recent meeting of state chapter presidents “strongly opposed an early endorsement of any candidate.”