ST. PAUL — Supporters of medical marijuana are trying to turn up the heat on Gov. Mark Dayton with a new TV ad that will debut in prime late-night and daytime slots.

Their ad features Angela Garin of St. Paul and her 5-year-old son, Paxton.

Garin says Paxton suffers hundreds of seizures a day from intractable epilepsy, but the seizures declined by 88 percent after he used medical marijuana. Garin said in an interview that she and Paxton traveled to Oregon, where medical marijuana is legal, to obtain the drug.

She says in the ad that she was shocked to learn that Dayton is blocking legalization of medical marijuana in Minnesota.

“Tell Gov. Dayton to support Paxton and to stop blocking access to medical marijuana,” Garin says.

Dayton’s office said it was preparing a response. Dayton has declined to support legalization without the support of Minnesota law-enforcement groups, but said it’s unfair to portray him as the sole obstacle on the issue.

Robert Capecchi, a spokesman for the Washington-based Marijuana Policy Project, said the nonprofit bought $10,000 in airtime for the ad to run through April 9.

It opens Wednesday night on Late Show with David Letterman and The Tonight Show with Jimmy Fallon. It was also due to run in dayside slots including Today and The View.