Sen. Kirsten Gillibrand (D., N.Y.) expressed openness Wednesday to prosecuting gun-owners who don't participate in a hypothetical mandatory buyback program for "assault weapons."

Gillibrand, a 2020 Democratic presidential candidate, told CNN she supported a buyback program as part of an overall ban on "assault weapons" and "large magazines." The term "assault weapon" is vague and can vary from state to state. It likely refers to some semi-automatic rifles like the AR-15 and AK-47, but it can also include some handguns and shotguns as well.

"On the assault weapons issue, you have talked openly about being in favor of an assault weapons ban," CNN anchor Poppy Harlow said. "I’m interested if you are supportive of a mandatory buyback program for assault weapons … Some have gone as far as to say not only should it be a mandatory buyback of assault rifles, but there should be criminal prosecution for those who don’t sell them back. Is that something you support?"

"So I think we should ban assault weapons as well as large magazines, and as part of passing that ban, do a buyback program across the country so that those who own them can be re-compensated for their money that they spent," Gillibrand replied. "But I think both of those ideas are strong."

"But mandatory," Harlow interjected.

"You don’t want people to retain them because if you make them illegal, you don’t want to grandfather in all the assault weapons that are all across America," Gillibrand said. "You would like people to sell them back to the government, so that you can make sure that people who shouldn’t have access to these weapons couldn’t have them."

Harlow repeated that if she supported a mandatory buyback program, Gillibrand would have to be for prosecutions resulting in "jail time" for individuals who didn't want to sell back their guns.

"Are you supportive of that?" Harlow asked.

"The point is, you don’t want people using assault weapons, and so the point is if you are arrested for using an assault weapon, you’re going to have an aggravated felony," she said. "The whole point is when you make it a crime to own an assault weapon, then if you are found using it, that would be the issue. It would just be part of your law enforcement in terms of what you have access to."

Gun control supporter Rep. Eric Swalwell (D., Calif.) made a mandatory buyback program the centerpiece of his short-lived presidential campaign, which he suspended in July.

Harlow framed Gillibrand as having the most "unique" stance on guns, due to her shift from a gun-rights supporter with an "A" rating from the National Rifle Association in the House to an "F"-rated U.S. Senator. Gillibrand has said she is "embarrassed" by her former stances on guns and immigration.

Gillibrand's campaign didn't return a request for comment.