DENVER — Whether bought from a downtown shop or cadged from a friend’s basement greenhouse, legal marijuana is easy to find in Colorado. Places to smoke it, not so much.

Smoking in private homes and on front porches is allowed. But under a thicket of state, local and private regulations, marijuana use here, in a state at the forefront of legalization, is banned from parks and sidewalks, airport smoking areas, hotel rooms, gallery events, nightclubs and nearly every other corner of public life. Smoking in public is regularly ticketed, and this spring, the Denver police raided two private, marijuana-friendly clubs and handed out citations.

But in the latest battle over legalizing marijuana, advocates are seeking to allow legal pot use to tiptoe ever so slightly into public, into establishments like bars or clubs that cater to over-21 crowds. Supporters are calling it “limited social cannabis use.”

In Denver, some of the advocates behind the 2012 vote that made Colorado, with Washington State, the first in the nation to legalize the sale and use of recreational marijuana, are now pushing to relax rules that they say have restricted marijuana use to a tiny number of appropriate places. Advocates say that the restrictions on use are too onerous and that they have created a paradoxical landscape where consumers, tourists in particular, are illegally consuming their legally bought marijuana in cars and alleys or on hotel balconies because there is nowhere else to use it.