Marijuana industry bigwigs paid $2,700 to hear Rand Paul speak at the National Cannabis Industry Association's business summit in Denver on Tuesday. Paul is the first major presidential candidate to raise money from the marijuana industry.

"This is a historical moment, that our industry is now working together with a presidential candidate," Tripp Keber, owner of Denver-based Dixie Elixirs, which makes cannabis-infused sodas and sweets, told the AP at Tuesday's event. Roughly 40 people paid to see Paul speak behind closed doors, which would have brought in more than $100,000 for his campaign.

Paul has been a longtime opponent of harsh marijuana laws. He's called long jail terms for marijuana use "ridiculous," and accused politicians in his own party of "hypocrisy" for admitting to past marijuana use, but failing to support drug reform.

The Marijuana Policy Project gave his policies a grade of A-minus — higher than any other presidential candidate.

In the Senate, Paul has co-sponsored a bill to end federal medical marijuana prohibition and backs sentencing reform for recreational use. He has yet to call for full marijuana legalization, but he said in remarks to reporters on Monday that the federal government should let states enact their own marijuana laws.

"I think the federal government shouldn't interfere," he said at a press conference in Reno, Nevada. "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."

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Paul would not answer questions about how he would have voted on Colorado's 2012 ballot initiative that legalized marijuana in the state. He instead spoke about making it easier for the marijuana industry to conduct business.

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

Marijuana businesses are excited to have Paul as an ally.

"It's the first event that we know of that a presidential candidate will be involved in the industry," Taylor West, deputy director of the National Cannabis Industry Association, told the Denver Post. "He's kind of in a class of his own."