Weed advocates don’t like this Mass. senator

State Senator Jason M. Lewis became perhaps the most public face of the opposition to Question 4, appearing at debates and forums to urge voters to cast their ballots against the measure.Jonathan Wiggs/Globe Staff

Marijuana advocates are trying to block an anti-legalization lawmaker from becoming the state Senate’s point person on pot, contending that his outspoken criticism of recreational marijuana makes him unfit for the position.

The advocates are lobbying Senate leaders not to appoint Senator Jason M. Lewis as the cochairman of the new Committee on Marijuana because Lewis was a key opponent of Question 4, which legalized pot purchase, possession, and use.

Jim Borghesani, who helped run the ballot campaign and now works for the national Marijuana Policy Project, said advocates don’t think the Legislature should tinker with the law at all before the marijuana oversight body it creates has time to make regulations.

“That said, if this proposed committee moves forward, we think the chairs should be as agnostic as possible regarding legalization and the law passed by voters in November,” Borghesani said in a statement. “A person who chose the role of chief campaigner against legalization would certainly not fit that description.”

Senate President Stanley C. Rosenberg and House Speaker Robert A. DeLeo announced last week that the Legislature will establish a joint Committee on Marijuana composed of members of both branches to draft legislation related to the new industry. Rosenberg and DeLeo will appoint the cochairs.

The Senate president offered high praise of Lewis in a statement.

“We are at the earliest stages of discussion with members about committee requests and interests,” Rosenberg said. “With that said, Senator Lewis has continually proven that he is one of the most thoughtful, knowledgeable, and hardest working members of the Senate.”

The marijuana committee is set to hold hearings, compile research, and write new laws on a variety of pot-related subjects. Those could include: hiking the tax rate on recreational marijuana sales; imposing restrictions on what form pot-infused food treats can take (a prohibition on marijuana gummy bears, for instance); and a legal standard for driving under the influence.

Lewis, a Winchester Democrat and onetime McKinsey & Co. consultant, led a special Senate committee on marijuana last year. He interviewed more than 50 experts, scoured the research, and studied the industry on a visit to Colorado.

But the 48-year-old father of two came to oppose the commercial marijuana market that the ballot initiative creates. And he became perhaps the most public face of the opposition to Question 4, appearing at debates and forums to urge voters to cast their ballots against the measure.

After the initiative passed, Lewis said he would respect the will of the voters.

But he raised the dander of some advocates by sponsoring a measure — now law — that delayed significant parts of a marijuana legalization law that 1.8 million voters approved.

Matt Schweich, director of state campaigns for the Marijuana Policy Project, the national group that helped back the Massachusetts initiative, met Thursday with Rosenberg.

Schweich declined to disclose what was said in that meeting. In a telephone interview, however, he did say his group wants the chairs to be “objective and neutral, and it wouldn’t be appropriate for a strong opponent to chair that committee.”