Retail shops selling marijuana may not open in Massachusetts until the middle of 2018 — or later — if lawmakers engaged in ongoing backroom discussions succeed in delaying parts of the legalization measure recently approved by voters, according to two people familiar with the conversations.
Some legislators are also angling to push back the Dec. 15 starting date for when residents could legally grow marijuana at home, the people familiar with the conversations said. It would still be legal to possess and use the drug starting Dec. 15, and lawmakers have not given any indication they plan to change that date.
The discussions mark the first indication of specific delays lawmakers are envisioning, after several state officials expressed concern about the timeline for implementing the voter-approved law.
Officials such as Treasurer Deborah B. Goldberg, who will oversee the new industry, have expressed worry that allowing stores to begin offering recreational marijuana in January 2018 — as stipulated in the ballot measure — would not give regulators enough time to set up appropriate oversight to protect public health and safety.
“We probably need to agree to extend the implementation date, so we can take an in-depth look at how the ballot question was written,” said House majority leader Ronald Mariano, a Quincy Democrat. Mariano pointed to the tax rate for retail marijuana sales and other licensing issues that he said were not adequately addressed in the referendum.
The legalization initiative, which passed 54 to 46 percent, is a law like any other, which means the House and Senate can change it through the normal legislative process.
There is preliminary talk of advancing legislation to adjust the measure in sparsely attended informal legislative sessions in the next few weeks. But that maneuver would require unanimous legislative agreement, because a single representative or senator can derail informal proceedings.
Mariano cautioned that, because of the nature of end-of-the-year sessions, any bill that could move before the new year would require a consensus.
“The only way it’s going to get done informally is if the House and Senate agree, and the governor’s willing to sign it,” he said.
Governor Charlie Baker has repeatedly emphasized he will uphold the voters’ will, but has expressed openness to changes in the marijuana measure for the sake of public safety.
“The administration looks forward to working with legislators and is committed to responsibly implementing the law, while adhering to the will of the voters,” said Baker spokeswoman Lizzy Guyton.
The potential actions of the Legislature left victorious proponents — Question 4 garnered more than 1.7 million votes in favor — dismayed.
“We don’t want to see anything changed,” said Jim Borghesani, spokesman for the Massachusetts legalization effort. “I don’t understand why the Legislature wouldn’t just let the regulators tackle the issues of legalization and then, with regulators’ advice, make any changes later.”
The law calls for the treasurer to appoint a three-member regulatory body, the Cannabis Control Commission. Borghesani said lawmakers should wait for the commission to create regulations and issue guidance to State House leaders before taking action.
Almost every top elected official in the state, including Baker and Mayor Martin J. Walsh of Boston, opposed the legalization referendum. So, too, did the Catholic Church and a statewide groups of doctors, hospitals, cities and towns, law enforcement officials, and businesses.
They expressed concern that the marijuana tax rate was too low to cover the cost of regulation and enforcement, that the language regulating marijuana-infused edibles such as brownies was too vague, and that protections in the law to ensure people under 21 don’t get the drug were too lax.
In TV ads, they warned about the risks of increased impaired driving and a proliferation of marijuana shops in hometown neighborhoods.
But their arguments did not move enough voters.
Senator Jason M. Lewis, an authority on the industry and a leader of the opposition, did not directly respond to questions about the legislative discussions on Wednesday.
But he said Senate President Stanley C. Rosenberg is meeting with leaders of the marijuana ballot campaign and other legalization advocates to “discuss how best to move forward together to implement the new law.”
Lewis, a Winchester Democrat, said that “we intend to fully respect the will of the voters. There are numerous issues and policy details that will need to be addressed by the Legislature. Our intention is to pursue a transparent and collaborative process that will engage all relevant stakeholders and members of the public, and to work as quickly and expeditiously as possible.”
Rosenberg, one of the few public officials to back the legalization measure, told reporters Monday that he plans to meet with legalization supporters in the coming days.
“We have a law that we have to implement, and it’s the will of the voters,” the Amherst Democrat said. “I’m going to be meeting with some of the proponents over the next week to have that conversation to assure them that we hear the voters voted. We want to work with them because we’re going to need to make some changes in the law. But we’re going to respect the principle here, which is: The voters have spoken.”
Also on Monday, House Speaker Robert A. DeLeo told reporters he will abide by the decision of voters. But the Winthrop Democrat said there will have to be changes to the law “to make it more implementable and, somewhat, for the safety of the people of the Commonwealth.”
Beacon Hill doesn’t have a sterling record when it comes to implementing voter initiatives.
The state’s earlier rollout of the voter-approved medical marijuana law was rife with charges of conflicts of interest, political favoritism, and questionable vetting of marijuana companies. Even though voters approved marijuana for medical use in November 2012, the first dispensary did not open until summer 2015.
If legislators tinker with parts of the referendum legalizing recreational marijuana, it will be a rare but not unheard of occurrence.
In 2000, voters passed a ballot initiative incrementally reducing the state income tax rate from 5.85 percent to 5 percent. The first ticks downward took place at the beginning of 2001 and 2002. But then the Legislature, facing tough economic times, froze the final tax cut.
Instead, legislators set a series of economic growth thresholds that would — more slowly than voters intended — lower the tax rate to 5 percent, but only if the state economy was humming along.
More than 15 years after Massachusetts voters spoke on that dollars-and-cents issue, the income tax rate still has not fallen to 5 percent.
Jim O’Sullivan of the Globe staff contributed to this report. Joshua Miller can be reached at firstname.lastname@example.org.