Former Vice President Joe Biden zeroed in this weekend on one of his top competitors, who many consider to have eclipsed him as the Democratic presidential frontrunner.

In an interview set to air on NBC's Meet the Press on Sunday, Biden waded into a controversy surrounding Sanders supporters who have been accused of threatening members of Nevada's Culinary Workers Union for not backing Sanders' Medicare-for-all proposal. Biden said Sanders isn't necessarily directly responsible for such behavior, but he's not sure he's done enough to put a stop to it, either.

WATCH: Former VP @JoeBiden says it is not "sufficient enough" for Bernie Sanders to "disassociate" himself from supporters' "misogynistic" attacks on Culinary Union leaders. #MTP Joe Biden: "I'd disown them. ... He may not be responsible for it but he has some accountability." pic.twitter.com/bABdpEtZLv — Meet the Press (@MeetThePress) February 16, 2020

Biden also criticized Sanders' policy proposals, arguing that while the senator has talked about Medicare-for-all for 35 years, he has nothing to show for it. Biden said people, like those in the Culinary Workers Union, have "broken their necks" to procure their current insurance, and he's not sure why Sanders wants to force them to give it up.

WATCH: Former VP @JoeBiden says Bernie Sanders has “never gotten anything done.” #MTP #IfItsSunday Biden: “He's been talking about health care, Medicare for all [and] universal health care for 35 years. Nothing's happened.” pic.twitter.com/D0dy6lhKSC — Meet the Press (@MeetThePress) February 16, 2020

And on Saturday evening, the former vice president put Sanders' 2005 vote to exempt gun manufacturers from liability in shootings on blast. He didn't name Sanders outright, but he called out "some of the people running for office" who voted for the exemption. Sanders, for what it's worth, has since changed his position on the matter. Read more at The Associated Press. Tim O'Donnell