The Democratic National Convention (DNC) kicks off this week with a promo video featuring U.S. President Barack Obama calling on the help of America's favourite fictional stoners, Harold and Kumar.

"Did no one tell the president that the Harold and Kumar series are drug movies? This strikes me as the equivalent of, say, if Jimmy Carter had enlisted the aid of Cheech and Chong," wrote journalist Charles Apple on the American Copy Editors Society blog.

The promo video for the DNC, which starts Thursday in Charlotte, NC, begins with the president making a rousing speech on what looks to be a very important phone call.

"Hey, this is Barack," he says, the music swelling. "Listen, I need to know if you're on board. OK, good. Because I'm counting on you. Everybody is. We have to get this right. So there's a lot at stake here. Just remember that I'm trusting you on this and I'll see you then."

It then cuts to Kal Penn and John Cho, reprising their roles as loveable stoners Harold and Kumar, sitting on a couch, watching TV and eating pizza. Kumar hangs up the phone.

"Dude, who was that? That sounded intense," says Harold.

"The president," replies Kumar.

"Sweet," says Harold.

The tie-in is that Penn - an outspoken Obama supporter - is hosting the convention, which will stream live on BarackObama.com.

The video comes as Obama faces criticism for cracking down on medical marijuana dispensaries, despite election promises not too.

The president has been open about smoking marijuana in college. Some reports say he was a member of a group of pot-smoking basketball players called "The Choom Gang."

"Barry Obama was known for starting a few pot-smoking trends," wrote David Maraniss, a Pulitzer Prize-winning author, in the book Barack Obama: The Story.

In his yearbook entry, he thanked "Choom Gang, and Ray for all the good times."

While the president has questioned the effectiveness of the US war on drugs, he is against legalization.