The debate here and in Washington State — where members of a pro-legalization group have also submitted what they say are more than enough signatures to secure a spot on the ballot — is premised on the idea that marijuana has become, if not quite mainstream, then at least no longer alien to the average voter. Medical marijuana is already legal in both states.

But greater familiarity with marijuana could be a double-edged sword, opponents say.

Medical marijuana dispensaries, especially in Colorado, have exploded in number in the last few years — some with medical-sounding names, others garishly suggestive in their names and imagery of the intoxicants on sale within. More than 88,000 Colorado residents have medical marijuana cards, according to the most recent state figures, with young men in their 20s and 30s — many of them suffering debilitating pain, according to their doctor-signed certificates — disproportionately represented.

And many Colorado communities have been actively debating medical marijuana — and saying no to it. Eighty-five Colorado communities have banned or halted openings of dispensaries, through popular vote or through their city councils or commissions, and where a municipality posed the question to voters, marijuana has lost 88.1 percent of the time, according to the Colorado Municipal League, an association of city governments.

The federal government, meanwhile, in states from California to Montana, has also been cracking down on medical marijuana growers and sellers who prosecutors say have gone beyond what their states allow.

Some critics of legalization say that medical marijuana’s growth, and the abuse of medicines that leak out to become recreational, foreshadows the dangers if accessibility is increased. Washington’s measure would be a statutory legal change, while Colorado’s would amend the State Constitution.