"Federal authorities are not going to turn their head and look the other way," Sarich says.
Roger Sherman, the leader of Colorado's anti-pot group shares similar concerns.
While Colorado's ballot amendment 64 doesn't outlaw driving under the influence of too much THC, Sherman says Coloradans could still face federal penalties for a state-sanctioned activity.
"You can still be engaging in illegal activity no matter how amendment 64 turns out," Sherman says. "The federal law is not going to stand idly by."
Sam Kamin, a professor of law at the University of Denver, says it's unclear what the federal government might do.
Kamin says the federal government has turned a blind eye to most of the flourishing medical marijuana industries popping up in Californian and Colorado.
"People are openly advertising and it is not secret they sell marijuana. The feds know where it is and they are not prosecuting it."
Most of the dispensaries the federal government have shut down have been asked to move because they are too close to a school zone. But, Kamin admits recreational use is uncharted territory,
"It is always a possibility that this whole thing could come crashing down," Kamin says. "Every transaction in every one of these stores is a violation of the control substances act, and we really don't know what we would get with a Romney administration."
The Obama administration has been vocally opposed to legalizing marijuana for recreational use. In 2010, when California tried to pass its own legalization effort, Attorney General Eric Holder publicly said he'd "vigorously enforce" the law, which prohibits the growth, distribution and use of marijuana.
But Holder has yet to speak out on the current marijuana legalization efforts, and Kamin says Obama's administration is likely to stay quiet until after the election.
"In a state like Colorado where Obama really needs the youth vote, cracking down on marijuana legalization doesn't seem to be in his political best interest," Kamin says.
Opponents to amendment 64 also argue that marijuana is bad for business.
"Every time there is a bust, a raid, every time the DOJ issues an opinion, the headline is Colorado," Sherman says. "It is like a bad rash that will never go away. We spent a lot of money trying to attract new business to the state, and this is not a selling point we can market," Sherman says.
But convincing constituents legalization is a bad idea in Colorado isn't cheap.
Colorado is a swing state and the cost of running a campaign here has skyrocketed. The anti-64 groups have raised $355,000 compared to the yes folks who have raised $1.8 million.
"The base of our campaign has been really grassroots, and we have been outspent 4-to-1," Sherman says. "This is not something that Coloradans have put on the ballot; this is something national groups have lobbied for."
Betty Aldworth, who leads the "yes on 64" campaign says that the campaign's raised money from both local and national fundraisers.