Watch A Tense Exchange Between Chris Christie And Cannabis Nurse

Chris Christie wants to be clear. Marijuana is a gateway drug that “lowers productivity” and is “causing enormous destruction” where it is legal. Marijuana is not medicine. And if you believe otherwise, well, “that’s your opinion.”

That was the gist of the New Jersey governor’s tense exchange with registered cannabis nurse and Gulf War veteran, Shelly Van Winkle, at an event in Newton, Iowa, last Wednesday.

Van Winkle had asked what Christie would do as president to balance states’ rights to legalize medical marijuana with the fact that federal law still considers marijuana a Schedule I drug, Think Progress reports.

“Let me be very clear,” he said. “As president of the United States, I will enforce the marijuana laws. Because I believe that marijuana is a gateway drug that causes our children and adults to use other drugs.”

When Van Winkle tried to interject that marijuana should be moved out of Schedule I to facilitate research of the drug, saying “cannabis is medicine,” Christie cut her off. “That’s your opinion. I respect your opinion, but I disagree with it.”

Christie told Van Winkle that as president, he would need an act of Congress to change the laws. “I could not administratively fix it and I will not administratively fix it,” he said. Van Winkle countered, “Under federalism, you could.”

“No, not under federalism. Federalism is a concept, it’s not a law,” Christie said.

At the second Republican presidential debate, Christie said, “In New Jersey, we have medical marijuana laws, which I supported and implemented ... I’m not against medical marijuana. We do it in New Jersey. But I’m against the recreational use of marijuana.”

His statements at the Iowa event are consistent, but reveal his strong personal opposition to marijuana. “Marijuana is causing enormous destruction," he said in Iowa. "If you go to Colorado and see what's happening in Colorado, and what downtown Denver looks like with those kinds of laws, that's where this country is headed."

Watch the full exchange here: