Mayor Martin J. Walsh, who spoke at length today about opposing a push to legalize marijuana, said he’s never smoked weed in his life — which even he admitted was “amazing.”

“I never have, which is amazing. I just never did. At this point, you can admit anything you did,” Walsh joked of politicians. “I drank plenty but I never smoked pot.”

Walsh has spoken openly about being a recovering alcoholic and his struggles with drinking earlier in his life. But as political leaders around the state turn an eye toward a likely ballot question in 2016 asking voters to legalize the drug, Walsh said he has major concerns.

“I don’t think I’d be the poster child” for the opposition, he said in the hallway outside the Boston Herald Radio studio. “If I’m out there advocating against it, that’s one thing. … But it’s not the only thing. It really has to be a grassroots efforts.”

Gov. Charlie Baker and Speaker of the House Robert A. DeLeo have said they’re also opposed to legalization, and both admitted they have smoked marijuana; DeLeo, for one, said it was a few times in his late 20s.

Asked if he’s ever smoked, Senate President Stanley C. Rosenberg answered by saying he went to college in the 1960s. But the Amherst Democrat has not directly said whether he opposes or supports legalization, only that he has concerns about how it could be worded in a ballot question.