Presidential hopeful Sen. Bernie Sanders (I., Vt.) said during a Sunday exchange with an undecided Iowa voter that a mandatory gun-buyback program is unconstitutional.

"A mandatory buyback is essentially confiscation, which I think is unconstitutional," Sanders said. "It means that I'm going to walk into your house and take something whether you like it or not. I don't think that stands up to constitutional scrutiny."

"Gun violence is an incredibly complex, large epidemic in our country," the voter said. "I am undecided right now, but I am choosing to definitely support a candidate who prioritizes that."

She then asked Sanders what his plan would be to "combat this epidemic," and whether he supported a mandatory gun buyback for AR-15s and AK-47s.

.@BernieSanders tells an Iowa voter mandatory gun buybacks don’t pass constitutional scrutiny: "A mandatory buyback is essentially confiscation which I think is unconstitutional. It means I am going to walk in your house and take something whether you like it or not." pic.twitter.com/9aBmcAb9eJ — Tom Elliott (@tomselliott) November 11, 2019

Sanders's campaign website proposes several measures to address gun violence including expanding background checks, prohibiting the purchase of high-capacity magazines, and banning the sale and distribution of "assault weapons" to civilians. The site also blasts the National Rifle Association as "a partisan lobbying public-relations entity for gun manufacturers" and calls for an end to its "corrupting effect on Washington."

The Vermont senator's history with gun control has drawn criticism in the past. Sanders previously supported a bill granting gun manufacturers extensive legal protections. He backpedaled on this stance in 2016, and announced his support for a bill that would repeal such protections.

Former Democratic presidential candidate Beto O'Rourke emphatically called for a mandatory buyback of all AK-47s and AR-15s during a Democratic presidential debate. O'Rourke defended his proposal as constitutional and endorsed sending police officers to collect the guns of citizens who do not comply with the buyback.

UPDATED: 4:52 P.M.: This article was updated to show Sanders made the remark on Sunday, not Monday.