President-elect Joe Biden’s incoming White House deputy chief of staff once touted "mandatory buybacks" of certain rifles 

Jennifer O’Malley Dillon previously served as Biden’s campaign manager – but before that, she managed Beto O’Rourke's 2020 campaign until he withdrew from the race.

The former Texas congressman declared during a Sept. 2019 primary debate: "Hell yes, we’re going to take your AR-15, your AK-47."

BIDEN'S CAMPAIGN MANAGER HEADED TO WHITE HOUSE AS DEPUTY CHIEF OF STAFF

A few weeks later, O’Malley Dillon appeared in a video, posted on O’Rourke’s YouTube channel, touting the campaign's plan for "mandatory" buybacks of certain firearms, in addition to a new ban on assault-style weapons.

"We are actually the only campaign with a plan…that supports mandatory buybacks of weapons of war,” she says in the video. "An assault weapon ban is very, very important, and we need to have it. But that only takes weapons of war off the streets in the future. It does nothing for weapons of war that are currently out there."

She estimated the mandatory buyback would affect "15 or 16 million" guns.

Vice President-elect Kamala Harris also said she supports a mandatory buyback of “assault weapons” on the 2020 primary trail, although she estimated her version of such a program would impact only about 2 million weapons.

A spokesman for the Biden-Harris transition team did not immediately respond to a request for comment.

Biden’s campaign has called for giving owners of "assault weapons or high-capacity magazines" the option to either sell their weapons to the government or register them with the Bureau of Alcohol, Tobacco, Firearms and Explosives under an expansion of the National Firearms Act.

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Police groups, Second Amendment advocates and even former Democratic presidential candidate Sen. Bernie Sanders have criticized the idea of mandatory buybacks – with the latter calling them “unconstitutional.”

Fox News’ Peter Hasson contributed to this report.