Rand Paul is fundraising with the cannabis industry (Andrew Burton/Getty Images)

DENVER — It looks like a boring trade show, with badge-wearing attendees and plenty of self-serve coffee machines. Except the booths advertise the "future of cannabis," a device that measures the potency of marijuana and sophisticated irrigation systems.

The marijuana industry is having its second annual trade show at the Colorado Convention Center, and there was a very special event on its sidelines: a presidential fundraiser.

Rand Paul tapped into a new money-raising well Tuesday: the marijuana industry, holding a private fundraiser at the National Cannabis Industry Association's business summit and expo here. The price to get into the closed-door event not far from the exhibition hall? $2,700.

The cannabis business was not legal during the 2012 presidential cycle and Paul is believed to be the first major presidential candidate to raise campaign funds from the industry.

"We are now establishing ourselves as a true industry with a professional focus and we have issues that we need to have dealt with on the federal level," said Taylor West, deputy director of the association. "We have candidates and elected officials who are seeing that need for reform."

Speaking to reporters Monday in Reno, Nevada, Paul said the federal government shouldn't meddle with states that want to legalize marijuana.

"I think the federal government shouldn’t interfere," he said. "One of the problems is the federal government has come into states that have allowed medical marijuana and still harass them so I think the federal government ought to stay out."

Paul said he would allow the marijuana industry to use the U.S. banking system, something from which it is currently prohibited from doing. Paul said he is concerned about potential "theft and crime" from a cash-only business and that taxes may not be paid because the money is not in a bank.

"I support legislation to allow them to do traditional banking and allow them to do traditional tax returns as well," he said.

Paul's view on full marijuana legalization is murky. Colorado, Washington and the District of Columbia have legalized specific quantities of marijuana for recreational use. Oregon will be added to the list Wednesday.

"I really haven’t taken a stand on," Paul said last year, "The actual legalization. I haven’t really taken a stand on that, but I’m against the federal government telling them they can’t.”

Paul co-sponsored legislation earlier this year that would end the federal prohibition on medical marijuana. It would allow veterans to be prescribed the drugs, make the banking system easier and facilitate limited interstate trade. Twenty-three states, the District of Columbia and Guam allow the medical use of marijuana, according to the National Conference of State Legislatures.

Paul has made reforming drug laws a centerpiece of his presidential campaign, calling for low-level offenders to receive treatment instead of being incarcerated, and abolishing mandatory minimum sentences for some crimes. Paul has called the war on drugs a failure and said that it has incarcerated a generation of black men. A fundraiser attendee told the Associated Press Paul spoke about the failures of the drug war.

Paul also held a rally at a sports bar here and closed door events to raise money on the last day of the reporting quarter. His campaign said the event was a private fundraiser at the convention center and it was not officially affiliated with the expo.

"Do we attract people there? Yes," a Paul aide said. "People know Rand's position on medical marijuana. People know his position on banking."

Mason Tvert, director of communications for the Marijuana Policy Project, said many in the cannabis industry are established and successful in business and have the money to show for it.

"These are people who founded other very large successful companies and have invested in other large ventures and in other cases are people who I believe may have been maxing out political donations to candidates in the past," he said.

Matt Kaplan, president of Sage Analytics, which manufactures a $20,000 device that will test the potency of  marijuana, stood at his booth and demonstrated his machine, which showed that a small amount of marijuana on a piece of glass was very, very potent, coming in at 29.4 percent THC.

"It's booming and part of the political lexicon," Kaplan said of the industry. "IT makes sense that politicians are attending these events."

Scott Simpson manned a table filled with packaging options, from tubes to tubs, touting "cannabis packaging supplies." Simpson said he believes Paul's overture to the industry will play well in Colorado, a state that will vote relatively early in the primary and caucus process, and already differentiates him from the very crowded 2016 GOP field.

"I certainly imagine it plays well in Colorado," he said. "I can't imagine Chris Christie would be coming here."