Massachusetts Democrats are flocking to their annual state convention to debate a new party platform and strategize ways to unseat Republican Gov. Charlie Baker.

The proposed Massachusetts Democratic Party platform calls for a single-payer health care system, free tuition at the state's public colleges and universities, and a $15 per hour minimum wage.

More than 5,000 delegates are expected to attend the Saturday convention in Worcester.

The three announced Democratic candidates for governor _ Newton Mayor Setti Warren, environmental activist Robert Massie and Jay Gonzalez, a budget official under former Democratic Gov. Deval Patrick _ will address delegates.

Baker, who remains popular in polls of Massachusetts voters, faces re-election next year.

U.S. Sens. Elizabeth Warren and Edward Markey also will address the convention. Warren is up for re-election in 2018.