A proposal to ban billboard, bus-bench and sidewalk sign-twirler advertising by Denver medical-marijuana dispensaries has pitted the state’s two most prominent cannabis trade groups against each other.

On one side is the Cannabis Business Alliance, which denounces the proposal by saying it creates too many uncertainties for the industry.

On the other is the Medical Marijuana Industry Group, which supports the proposed ban by arguing that it is a show of neighborliness for an industry that is not always embraced.

The debate comes to a Denver City Council meeting Monday evening, when there will be a public hearing on the proposed ban.

The proposal would eliminate outdoor medical-marijuana ads in the city, except for signs on the businesses themselves.

Dispensaries would still be able to advertise in newspapers and magazines and would also be able to display their logos on items for charity events they sponsor.

The ban, proposed by council members Christopher Herndon and Debbie Ortega, expands upon a separate proposal by Ortega that would ban outdoor medical-marijuana advertising within 1,000 feet of schools, day cares and parks. That proposal is still alive but is expected to be supplanted by the citywide ban should it survive Monday night.

“I think this is in the best interests of our children across the city,” Ortega said of the broader ban.

In making that argument, Ortega has picked up an unlikely ally in the Medical Marijuana Industry Group.

Mike Elliott, the group’s executive director, said a citywide ban creates a level playing field for all dispensaries and addresses some of the most persistent complaints that officials receive about dispensaries — advertising that is too in-your-face.

“Because we want to be good community members,” Elliott wrote in a statement, “we can make reasonable concessions that satisfy community concerns.”

But Kristen Thomson, a spokeswoman for the Cannabis Business Alliance, said the proposed ban’s reach isn’t clear. She questions, for instance, whether dispensaries would be able to give branded T-shirts or coffee mugs to customers as a reward for loyalty.

And while dispensaries can display their logos at sponsored charity events, could they do the same at sponsored trade fairs or street festivals?

While Thomson said her organization isn’t opposed to ad restrictions — the group is supportive of a ban around schools and day cares — the citywide ban, she said, goes too far.

“It’s pretty short on specifics,” Thomson said, “and for us it leaves many unanswered questions.”

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