Senate President Stanley Rosenberg said he expects some lawmakers to attempt to repeal marijuana legalization next year, speaking in an interview one day after the legislature acted abruptly and without public debate to delay the opening of weed shops.

“Believe me, people have rights. I’d very surprised if people didn’t offer an amendment … to repeal the question. I would not be surprised if someone did that,” Rosenberg said this morning on Boston Herald Radio, though the Amherst Democrat, who supported legalization, quickly added, “It doesn’t mean that it would be passed. This will not be an easy debate.”

Marijuana was legalized by a ballot measure passed by voters last month. Under the new law, recreational marijuana stores were slated to open in January 2018.

Yesterday, just a half-dozen lawmakers were on hand to pass a bill pushing pot shop openings back six months to July 2018. Rosenberg staunchly defended the move, saying it came after warnings from regulators in Colorado that the original timeline passed in the Bay State ballot question was too optimistic.

The bill, which now sits on Gov. Charlie Baker’s desk, prompted a swift outcry from legalization supporters, who complained of the legislature’s rush to act amid a sparsely attended informal session.

Rosenberg pushed back, saying he had “constant communication” with advocates, though he admitted they had not seen a draft of the legislation before lawmakers passed without a roll call vote.

“But they knew exactly what was going to be in the bill when it came to the floor because there had been communication with them repeatedly,” Rosenberg said. “This is not the end of the world. It’s a small delay, it’s a short delay. People will get what they need. We are not going to undermine the will of the voters.”

Lawmakers had for weeks indicated they intended to move to change language of the bill, though the exact details didn’t emerge publicly until the morning of the vote. Rosenberg said state Treasurer Deborah Goldberg, whose office will oversee the nascent industry, had wanted as much as a two-year delay before lawmakers settled on the six-month timeframe behind closed doors.

Jim Borghesani, a spokesman for the group that pushed the ballot question, said advocates were notified “late the night before” of the vote but still disagreed with the way lawmakers did it.

“I think to take a measure that was passed by a very solid majority on Nov. 8 and do something on that in informal session, that’s not the way we would have liked to see it done,” he said on Herald Radio today, pointing to the question’s 7-point margin on election day.

But he added that he’s taking Rosenberg, Baker and Speaker of the House Robert DeLeo at their word when they say they plan to honor the law’s intent even as they seek to make changes.

“We don’t think they’d try to kill this,” Borghesani said of legalization.