Marijuana initiatives: Why three alternatives to Amendment 64 didn't make ballot

Last February, when Amendment 64, the Regulate Marijuana Like Alcohol Act, was approved for the November ballot, backers of several other pot-related measures, including Initiative 70, Legalize2012's proposal and the Relief for the Possession of Cannabis Act, were trying to duplicate this feat. But at the Monday deadline set by the Colorado Secretary of State's office, none of their proponents submitted any signatures -- meaning voters won't get the chance to consider their proposals. How close did they come to consideration? And what obstacles proved insurmountable?