As the nation’s first state vote on whether to legalize marijuana for recreational use nears, a new poll has introduced fresh uncertainty into the race.

After weeks of riding a wave of positive poll results, supporters of Proposition 19 were handed a head-scratcher on Tuesday when a Reuters/lpsos poll found 53 percent of California voters opposed to the measure. The same polling company found voters nearly deadlocked on the issue in June. Also troubling for the "Yes on 19" side are media reports that it is out of money.

Opponents of marijuana legalization say the poll shows that Californians are turning against Prop. 19 as they learn more about it. Prop. 19 backers are painting the poll as an anomaly.

Future polls should offer more insight into whether the Reuters/Ipsos poll is off base or whether it is picking up a shift in the race.

“Either this poll is way off, or they are picking up something that no one else has so far," says Ethan Nadelmann, founder and executive director of Drug Policy Alliance, a national organization that backs legalizing and regulating marijuana.

New poll: outlier or indicator?

He notes that a Sept. 21 California Field Poll, a Sept. 26 PPIC poll, and an Oct. 3 SurveyUSA poll all found more support than opposition for Prop. 19 among California voters.

Proponents of Prop. 19 point out that the questions in the Reuters/Ipsos poll use different descriptions than the wording in the initiative itself. Moreover, they suggest that the small sample size of the poll may also have accounted for why the results differ from several others.

"All of the evidence points to this latest poll as being an outlier compared to all the others showing us ahead,” says Yes On 19 spokesman Tom Angell.

The Reuters/Ipsos poll's findings on the two major political races in the election – for Senate and governor – also don’t square with the other polls, say backers.

But opponents of legalization say the new poll results reflect the fact that 24 state newspapers have come out against Prop. 19 in recent weeks.

“We feel these editorial positions are getting to the undecided voters,” says Roger Salazar, spokesman for the No On Proposition 19 campaign. “[Voters] held off making their decisions until they weighed the pros and cons and now have made up their minds.”

As to the cash-flow question, Prop. 19 hasn't drawn the kind of heavy money that usually infuses issues campaigns. Just $2.5 million has been raised on both sides, according to Kim Alexander of the California Voter Foundation, with the “yes” campaign raising nearly $10 for every $1 brought in by the opposition.

Facebook co-founder Dustin Moskovitz recently gave $50,000 to the pro-legalization campaign, but otherwise it is relying on an animated force of volunteers and hundreds of smaller donations.

Can Prop. 19 work?

Meanwhile, both sides are trying to address the issue of how the proposition might be implemented if it passes.

On Wednesday Assemblyman Tom Ammiano introduced legislation that would establish a uniform statewide regulatory system for marijuana under the California Department of Alcoholic Beverage Control. The bill would leave cities and counties the option to regulate marijuana sales themselves.

The bill undercuts several assertions by Prop. 19 opponents, says Mr. Angell of Yes On 19. First, “that the money generated by marijuana sales won’t make it to the state,” he says. And second, that "this is a regulatory nightmare, because it creates so many different regulatory bodies.”

Cities have already begun to take up these questions. In anticipation of Prop. 19 passing, nine California cities – including San Jose, Stockton, Oakland, and Sacramento – have initiatives on the Nov. 2 ballot asking voters to decide about specific taxation rates for marijuana.

But opponents of legalization aren't placated by those arguments. “They’re trying to tell the people, ‘Don’t worry, we’ll fix this later,’ ” says No On 19's Mr. Salazar. “They know the public isn’t buying their regulatory scheme."

While supporters of Prop. 19 claim the measure will generate $1.4 billion for state coffers, Salazer points to the California State Board of Equalization’s updated analysis of Prop. 19, which refutes those claims. The study concludes: “It is not possible to estimate the potential revenue gain” of Prop. 19.

Those findings have provided the “no” forces with the confidence they say they need down the stretch.

“We are ... talking to the public up and down the state because we feel that if they get the right information about this initiative, they will vote no,” says Salazar.