Medical marijuana supporters are airing a new ad on Minnesota TV stations that criticizes Gov. Mark Dayton for not supporting a proposal at the Capitol to legalize it.

The ad features a Minnesota mother with a five-year-old son who suffers a rare disorder she said causes him multiple seizures every day. Angela Garin of Inver Grove Heights said her son Paxton's seizures were drastically reduced with exposure to medical marijuana on a trip to Oregon, where the family was able to access it legally.

In the ad, Garin urges viewers to "tell Gov. Dayton to support Paxton and stop blocking access to medical marijuana."

Heather Azzi of Minnesotans for Compassionate Care said the ad was paid for by the Marijuana Policy Project, a Washington, D.C.-based group that advocates nationwide for medical marijuana legalization. She would not disclose the cost of the ad buy but said it is statewide.

The ad is set to start airing Wednesday night during the Tonight Show with Jimmy Fallon and the Late Show with David Letterman, and then during several morning news and talk shows on Thursday. Azzi said the group is likely to air a second ad starting next week.

A bill to legalize medical marijuana in Minnesota has been much discussed at the Capitol this year, but has made little legislative progress. Advocates are planning a news conference outside Dayton's office on Thursday to deliver a petition in support of the bill. Advocates have been particularly critical of Dayton, alleging that in a recent private meeting with medical marijuana supporters that the governor suggested they could buy the drug illegally. Dayton has denied that.

The ad can be viewed here.