Colorado lawmakers yanked and tugged at the threads of the state’s proposals for regulating recreational marijuana on Thursday, as one legislator hinted to his colleagues that pulling too hard could unravel the whole thing.

At its second meeting, the legislature’s joint marijuana committee returned again to the question of how to structure the marijuana stores that Colorado voters authorized in November. A task force that suggested policies for lawmakers recommended the industry be vertically integrated as are medical-marijuana businesses — meaning stores would have to grow what they sell.

But two lawmakers questioned whether that runs against the intent of the marijuana-legalization measure, Amendment 64, which doesn’t prescribe a system where growers are linked to retailers.

The recommendation would also provide a one-year window where only people who currently own medical-marijuana businesses would be allowed to apply to run recreational marijuana shops. Rep. Brian DelGrosso, R-Loveland, said he worries such a restriction “gives existing businesses a foothold, essentially a monopoly” on the new industry.

Other lawmakers raised concerns about one proposed requirement that people live in Colorado for two years before they be allowed to own a recreational marijuana business and about another that would block people convicted of a drug felony from ever owning a marijuana business.

Rep. Dan Pabon, a Denver Democrat who served on the task force and helped write the proposals, said the goal is to get the regulations running quickly and to prevent leakage of marijuana from the regulated system into the black market. For that reason, the task force borrowed heavily from medical-marijuana law and made selective compromises.

“I hope that the committee is appreciating the interconnectedness of all these recommendations,” Pabon said. “If you push on one lever, it pushes on another piece of the overall package.”

Sen. Cheri Jahn, a Wheat Ridge Democrat and another task force member, said some of the regulations — such as vertical integration — would be re-evaluated after a few years.

Despite the extensive debate Thursday morning, the committee did not take any formal votes. During a straw vote, a majority of committee members supported requiring recreational marijuana stores to have to grow only 70 percent of what they sell under a possible vertical integration model. The remaining 30 percent could be bought from other stores, in a model similar to medical marijuana.

The committee’s next meeting is Friday at 1:30 p.m. The group has until the end of the month to work the task force’s 58 recommendations into a bill, which would have to clear the entire legislature by the end of the session on May 8.

The state must begin taking applications for recreational marijuana stores this fall. The first shops could open around Jan. 1, 2014.

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/john_ingold