Senate President Stanley Rosenberg says lawmakers have to be prepared to do a “deep dive” into the debate over legalizing marijuana, saying both legislation and an expected 2016 ballot question push are coming whether they like it or not.

“The point of this exercise it to do a very deep interdisciplinary dive into the subject matter,” the Amherst Democrat said on the Boston Herald Radio show “Morning Meeting” today. “If we’re going to participate appropriately in the debate as the legislation moves through and the ballot question (is prepared), we have to do a deep dive.”

Rosenberg, in structuring the Senate and his leadership team this week, created a special committee, headed by Sen. Jason Lewis, to study the legalization of the recreational use of marijuana, moving a topic many pols on Beacon Hill have dodged for years quickly up the list of priorities for the Senate.

Rosenberg, speaking to a Herald reporter after his appearance, declined to say whether he’s personally for or against legalization, twice saying he wants “to learn a lot more.”

When asked on Herald Radio whether he has ever smoked marijuana he responded, with a laugh: “Did I go to college in the ’60s?”

Advocates for legalization have argued that Massachusetts voters have steadily moved toward accepting legalization, pointing to past successful ballot questions decriminalizing small amounts of the drug and in 2012, legalizing the use of medical marijuana.

But nearly a 2 1/2 years later, not a single medical marijuana dispensary has opened and the process has been marred by delays and questions under the Department of Public Health. Rosenberg put the blame, in part, on a ballot question that was “so badly written” by a small group of advocates who, like those behind other ballot questions, “don’t have to take into consideration a lot of other people’s ideas and opinions.”

“Then if it passes, the say you can’t amend it in the legislature because it’s the peoples law,” Rosenberg said. “So when you’re dealing with something as controversial as marijuana, if we don’t have robust research and conversation on the subject, then we’re leaving a lot of stuff on the table.”

As an example, Rosenberg pointed to a debate of how old someone should be to legally smoke marijuana, adding that research shows people’s brains aren’t fully developed until they’re 25 to 27 years old. When hosts Hillary Chabot and Jaclyn Cashman gave different opinions — one saying 18 years old and the other 21 — Rosenberg used it to prove his point that the legislature should be involved.

“Here we go, we have a disagreement already,” he said. “Who’s going to arbitrate that conversation?”

Rosenberg discussed a range of other topics during his BHR appearance:

• The veteran legislator, considered one of the most liberal in the Senate, said he hasn’t decided who to back in a 2016 Democratic presidential primary. He said he didn’t support potential 2016 candidate Hillary Clinton in her 2008 run against Barack Obama. In a hypothetical conversation with Sen. Elizabeth Warren, he said would tell her, “Wherever you sit I’m excited about your leadership,” though he made it clear he wouldn’t push her to run given she’s continually said publicly she’s not interested.

But Rosenberg said he does plan to be active in the New Hampshire primary, where he’s held signs and knocked doors for candidates for roughly the past 30 years. “You are likely to see me up there (again),” he said.

• Rosenberg said he’s in favor of tackling legislation toughening penalties for those who protest on highways, a debate sparked last week when dozens of demonstrators tied up traffic on I-93, forcing at least one ambulance with a car crash victim to divert its route to a Boston trauma hospital.

Some lawmakers have already filed legislation, including one that would make it a felony, though Rosenberg declined to back any particular bill.

“There should be consequences,” Rosenberg said. “Absolutely, that’s why it’s going to be reviewed and we’re going to figure out an appropriate sanction for that situation.”

• Rosenberg said he agrees with Speaker of the House Robert DeLeo that the Boston bid for the 2024 Olympic Games should include sites across the state, including in western Mass.

“Massachusetts is a pretty small state,” he said. “This isn’t Texas or California where you’re going to drive for days to get from one end to the other. Why can’t we have events in other parts of the commonwealth? Let’s spread it out.”

He said his main concern is protecting taxpayers from picking up a last-minute bill to cover the Games’ costs. “First we need to bring in some very smart people who can help us understand and evaluate this proposal,” he said. “It’s kind of in the show-me state at this point. Trust but verify, or show me. Because we need to make sure we’re not going to be handed a bill at the end of the day.”