Sanders launches Florida TV attack ads on Biden.

Bernie Sanders is attempting to undermine two of Joe Biden’s key selling points with a round of ads his campaign is running in Florida in the runup to the March 17 primary.

The senator from Vermont is pushing the claim that Biden has a history of attempting to cut Social Security in a spot called “Protect Social Security.” In another, he’s is using audio of President Barack Obama to vouch for him.

Biden’s most important group of supporters has been voters older than 45, including seniors on Social Security and others close to receiving it. Sanders gets his support from younger votes.

The “Protect Social Security” ad uses audio of Biden saying a federal budget freeze would have to include everything, including Social Security. Sanders is depicted as a defender of Social Security and calls instead for expanding benefits.

When the candidates went back and forth over Social Security in January, PolitiFact found that a Sanders video at the time “didn’t tell the full story” about Biden’s record on Social Security. “Biden and Sanders each highlight the part of Biden’s 40-year record that’s favorable to their own arguments.”

And one of Biden’s most prominent selling points is his eight years of faithful service as Obama’s vice president. Obama hasn’t endorsed in the race, but a close associate, former National Security Adviser Susan Rice recently endorsed Biden, a move seen by many as an indication of Obama’s sentiment.

Sanders is attempting to undercut that with his “Feel the Bern” ad, using images of Sanders and Obama along with audio of Obama saying nice things about the Vermont senator. It’s not unheard of for a politician to use the words of someone to make it seem like an endorsement. There are countless hours of Obama saying all sorts of nice things about political leaders.

The left leaning website Mediaite said the ad “cobbles together positive things that President Obama has said about Sanders in the past” that was “deceptively edited.”

Mike Bloomberg, who dropped out on Wednesday, did the same thing as the Sanders ad, with a spot containing all sorts of positive comments from Obama. It’s notable for Sanders, because Obama isn’t believed to think terribly highly of Sanders, especially since he considered a 2012 primary challenge when Obama was running for re-election.

The Sanders campaign said the new ads were running in Arizona, Florida, Idaho, Illinois, Michigan, Mississippi, Missouri, Ohio, and Washington — all states that have primaries on March 10 and March 17.

Sanders spokesman Kolby Lee declined to say how much the campaign is spending on the ads in Florida, what media markets they’re running in, and which spots are running where. A third ad, in which an autoworker talks about his community being “decimated” by trade deals, is targeted more toward industrial states such as Michigan, which have voters who have been more affected by trade agreements.

The Biden campaign declined to comment on the Sanders ads.