BOSTON — The chairman of insurance giant Progressive Corp. this year provided another $465,000 for a ballot question to legalize medical marijuana in Massachusetts.

Peter B. Lewis, who supports medical marijuana, has now contributed $990,000, including $525,000 last year, to the Committee for Compassionate Medicine, the organization leading the effort to legalize medical marijuana in Massachusetts. Lewis is nonexecutive chairman of Progressive, which is based in Mayfield Village, Ohio.

According to reports filed with the state Office of Campaign and Political Finance last last week, the Committee for Compassionate Medicine has raised $512,850 this year and spent $405,825. Including last year, the committee has now raised $1.039 million and spent $924,000.

The group opposed to medical pot raised $600. Voters will decide medical marijuana and another statewide ballot question on Nov. 6.

The ballot question would make Massachusetts the 17th state, including Maine and Rhode Island, to have laws allowing the medical use of marijuana.