President Obama got an endorsement from a medical marijuana group. (Nikki Kahn/THE WASHINGTON POST)

Even more surprised? Mainstream marijuana activists, many of whom have never heard of the organization or its founder, Tom Leto. The major lobbying and advocacy groups have so far held off on endorsing a presidential candidate — they say Obama hasn’t lived up to a vow to back off raids.

“Our whole community was asking ‘who is this clown?’” says Aaron Houston, executive director of the Students for Sensible Drug Policy. And conspiracy theories, unsurprisingly, bloomed.

The U.S. Medical Marijuana Chamber of Commerce’s press release endorsing Obama claimed it has 10,000 members in chapters across the country, and its Web site lists a box-office address on a swank stretch of Pennsylvania Ave.

The group does not appear to be incorporated, nor is it listed in nonprofit records or in Dun & Bradstreet. A lone press clip from a 2010 event in New Jersey is the only mention to be found.

We reached Leto, who said the fact that no one had heard of him meant he has more work to do. As for the lack of a paper trail, he says it’s in the works. “I’ve got attorneys working on all that,” he says. “It’s a process, you know? We will be...I don’t know how to say it, but lock, stock, and barrel in about two weeks.”

Leto says he’s not naming his members to protect them. “People aren’t ready to be out there,” he explains. “but I’m out there and I’m in it to win it.”

Leto, a California-based promoter of hydroponic equipment, explained the gen­esis of the company, a story that only adds a bit of mystery: he was working with the New York PR firm Todd Shapiro Associates to help market his hydroponics business when the concept snowballed into a nationwide organization advocating federal legalization of medical marijuana.

Shapiro referred our questions to his office, but the person we spoke to there said she wasn’t authorized to speak on the record.

Still, pot advocates are wary. Paranoid, even. But then again...