Boston Mayor Martin J. Walsh responded to criticism from a pro-marijuana legalization group that called him a “hypocrite” for opposing pot legalization while supporting measures they say promote easier access to alcohol — such as keeping bars open later and granting more liquor licenses — by challenging the group to make its case for legalization.

“I am not going to get into name calling, they can call me whatever they want,” Walsh said. “What I would like to ask them to do … is to explain to the people of Massachusetts why it’s important to legalize marijuana. I think that would be a good start for the campaign.”

The group, the Campaign to Regulate Marijuana Like Alcohol, leveled the charge one day after Gov. Charlie Baker, Walsh and other top officials announced the formation of a committee to fight a likely November ballot question that ?would legalize recreational marijuana.

The group unveiled a poster outside the State House showing the faces of Baker and Walsh, who is a recovering alcoholic, with a speech bubble that read: “Our Health Policy: Drink More Alcohol.”

Will Luzier, campaign manager for the pro-marijuana group, said pot was less toxic and less addictive than alcohol “and does not contribute to violent or risky behavior.”

Lizzy Guyton, a spokeswoman for the governor, said Baker believes voters should get more than “unfortunate and insensitive attacks from those seeking to open a new billion-dollar commercial marijuana industry in the commonwealth.”

Walsh said past efforts to change marijuana laws have made persuasive arguments and he challenged this group to do the same.

“In the past there has been the argument for the decriminalization of marijuana and the folks that fought for that made an argument, and a good argument, for why marijuana should be decriminalized,” Walsh said. “The next step was medical marijuana and folks who advocated for that made a good argument for why medical marijuana should be allowed in Massachusetts. I am not quite sure why marijuana should be legal in Massachusetts.”

Herald wire services contributed to this report.