Massachusetts Democrats gathered in Worcester for their state party convention Saturday as they seek to regain the governor’s office and retain control of virtually every other source of political power in the state. Attorney General Maura Healey and state Sen. Sonia Chang-Díaz are both hoping to win the top office in November, but they must first go head-to-head in the fall primary. Healey won the party’s endorsement with 71% of the delegate votes Saturday, while Chang-Díaz won 29%, enough to get her name on the September primary ballot. Whoever wins the primary will face off against the victor of the Republican run-off.