In the final week, the Yes On Prop. 19 campaign received a million dollars from billionaire investor George Soros for new ads.
Celebrities endorsed the measure. Even rapper Snoop Dogg smoked a joint on camera to show his support, but the measure failed, losing 46 to 53 percent.
Amanda Rain, a spokesperson for the Yes On Proposition 19, says her campaign doesn't feel like losers Wednesday.
"What we've done is we've changed the debate on cannabis, and it's no longer a matter of 'if,' it's a matter of 'when,'" said Rain.
Proponents say they're now looking to putting the issue on the 2012 ballot. Rain says a midterm election may not have been the platform to pass such a measure.
"Midterm elections are historically conservative and so I think that that was definitely a play here," said Rain.
"After a serious statewide debate on this issue, they are not ready to legalize marijuana in the state of California," said Covina Police Chief Kim Raney. "I think it comes down to that."
Raney, who worked on the No On 19 campaign, said U.S. Attorney General Eric Holder threatening to sue California influenced a lot of voters in the end.
"Over the course of the last month to two months, as the voters and as the newspaper editorial boards really started to peel back the layers, they saw how problematic this initiative was," said Raney.
The most recent SurveyUSA poll indicated the majority of the measure's opponents voted by absentee ballot.
Many supporters had yet to vote and there is a question about how many actually showed up at the polls Tuesday.
Still, supporters say even with a lack of young voters, they're convinced marijuana will eventually become legal. They say 19 just started the debate.
"I think that the legalization comments just on how it would affect the black market -- I don't know -- I thought it would be a positive thing," said Silver Lake resident Amanda Norman.
"I've got a 7-month-old daughter, and I just don't want her going to kindergarten and having to walk through a waft of pot smoke," said Glendale resident Rob Johnson.
Supporters say Tuesday's election was just the first round of their efforts. Along with California, they hope to have similar measures on ballots in Washington and Oregon by 2012.