At the second Republican presidential debate, New Jersey Governor Chris Christie claimed that he’s “not against medical marijuana.” But his exchange with a registered cannabis nurse this week seems to suggest otherwise.

On Wednesday at an event in Newton, Iowa, cannabis nurse and Gulf War veteran Shelly Van Winkle asked Christie how he would balance states’ rights to legalize medicinal marijuana with the fact that federal law still considers marijuana a Schedule 1 drug. Would he do anything to address the confusion?

The exchange got tense, quickly. Christie said he would enforce the existing federal laws criminalizing cannabis, and said he would not act administratively to change them. And when Van Winkle countered that “Cannabis is medicine,” Christie disagreed:

Christie: “That’s your opinion. I respect your opinion, but I disagree with it. Now, there are limited instances in [New Jersey] where we allow folks to use marijuana for medical purposes, but it is a medical program and it’s for only certain, specific diseases — you have to get a doctor to write a prescription for it. Those doctors have to be registered with the state, and we have to monitor what they’re doing.” Van Winkle: “But under federal law, a doctor can’t write a prescription. They can only recommend. Because it’s a Schedule 1 substance. That’s the problem.” Christie: “You’re asking me what I would do as president. I’m not going to get into a debate with you. You and I have different views.”

Christie then argued that as president, he wouldn’t be able to change the medical marijuana laws either way. Instead, he said, he would need an act of Congress to change the laws.

Christie: “I could not administratively fix it and I will not administratively fix it.” Van Winkle: “Under federalism, you could.” Christie: “No, not under federalism. Federalism is a concept, it’s not a law. Okay? “

Christie then accused Van Winkle of not wanting a real answer to her question.

“Listen, do you want an answer? Or do you want to continue to video me, so that you can use that and put it on the internet? Because that’s what this is about. And I’ve had this done to me in other states as well,” Christie said.

Watch it here: