BOSTON — Travel guru Rick Steves is set to tour Massachusetts in support of a pro-marijuana ballot question.

Steves is host of the PBS series “Rick Steves’ Europe” and a longtime advocate of easing marijuana laws.

Steves plans to make three stops across the state next month to stump for the question, which would legalize the recreational use of marijuana.

In a statement, Steves said there are many reasons to end the prohibition on pot, including redirecting money from criminals and into state coffers. Steves plans to donate up to $100,000 to the question.

Republican Gov. Charlie Baker, Democratic Attorney General Maura Healey and Democratic Boston Mayor Marty Walsh oppose the question. They say legalizing pot could be a gateway to harder drugs, including opioids, which have caused a crisis in Massachusetts.

In Maine, the well-known travel writer donated $50,000 to Yes on 1, the political action committee that’s backing a November referendum effort to legalize the recreational use of marijuana. He is also scheduled to come to Maine in October to stump for the referendum campaign.

If the marijuana referendum is approved in Maine, adults could possess up to 2½ ounces of marijuana and cultivate up to six plants for personal use. Marijuana use would be prohibited in public, with violations punishable by a $100 fine. The bill also would apply a sales tax of 10 percent to retail marijuana and marijuana products.

Steves is a resident of Washington state and has worked for legalization there and in Oregon.