Marijuana advocates late Monday fought back an effort that could have halted Colorado’s plans for legal marijuana shops, ending a debate that swept through the state Capitol like a dust devil for a little more than three hours.

The proposal, Senate Concurrent Resolution 3, would have put two separate constitutional measures before the voters in November. The first would have asked voters to approve special sales and excise taxes on recreational marijuana. If that measure failed, a second measure would have asked voters whether they wanted to suspend recreational marijuana sales.

The resolution was introduced at about 6 p.m. on the third-to-last day of the legislative session — the absolute last moment it could have been formally proposed. It was sponsored by two dozen senators, including Senate President John Morse. And it cleared a Senate committee less than an hour after it was introduced.

But facing a midnight deadline for initial approval in the full Senate and a handful of lawmakers committed to defeating it, Morse adjourned the Senate for the night at about 9:30 p.m. without taking up the resolution. Under legislative terminology, the newly introduced resolution was suddenly “dead on the calendar.”

Morse said the measure was an attempt to force marijuana advocates to support the ballot measure on pot taxes.

“If the tax measure is unsuccessful in November, the taxpayers will be left holding the bag,” Morse said Monday night. “And I can assure you that the Colorado legislature will take up this issue again if that happens.”

Pot sales, at specially licensed marijuana stores, haven’t even started yet but were authorized by Amendment 64, a marijuana-legalization measure that voters passed just last year. The resolution introduced Monday would have suspended the sales until voters approve taxes to fund regulation of those stores.

The measure wouldn’t have affected Amendment 64’s portions that legalize use and limited possession of marijuana for adults.

The resolution created chaos in the halls of the Capitol, as advocates and lobbyists scrambled to find copies of the resolution — which had not been posted online when the committee debated it — and raced to testify before the committee.

“I don’t see how this is anything more than an affront to our system of government and how we do things here,” Christian Sederberg, one of the authors of Amendment 64, said.

Morse said the resolution was an attempt to get marijuana advocates’ attention to support pot taxes. A separate measure at the Capitol, House Bill 1318, proposes a 15 percent excise tax and a special sales tax initially set at 10 percent on marijuana. Voters would have to ultimately approve the taxes.

Lawmakers in the Senate must give initial approval to that bill, plus another bill on marijuana-store regulations, by midnight Tuesday or they too die for lack of time left.

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