By Michael Norton

State House News Service

BOSTON — Many Democrats on Beacon Hill are behind Hillary Clinton’s campaign for the Democratic presidential nomination.

Acton Sen. Jamie Eldridge is not among them.

Eldridge on Saturday plans to officially endorse the candidacy of Sen. Bernie Sanders of Vermont and help Clinton’s rival open his first official campaign office in Massachusetts.

Sanders supporters are set to gather at 10 a.m. Saturday to open his Massachusetts headquarters at 89 Cambridge St. in Charlestown.