DENVER (AP) -- It's day one for pot legalization backers gathering signatures for a Constitutional Amendment seeking to authorize pot for recreational use in Colorado.
Supporters need about 86,000 signatures to get the question on ballots next year. They start collecting signatures Thursday afternoon in Denver.
If approved, the amendment would make pot legal in small quantities for adults over 21 starting in 2013. Sixteen states allow medical marijuana, but Colorado's proposal would set up a federal showdown over recreational pot rules.
Backers of the amendment say the time is right to seek full legalization.
Some pot activists say the measure includes too much regulation and plan to propose a rival suggestion.
Colorado voters rejected a marijuana legalization measure in 2006.
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