INDIANOLA, Iowa — Joe Biden ripped into Vermont Sen. Bernie Sanders and his campaign over what he believes is a smear about his past views on entitlements.

The comments came during question and answer session at an Indianola town hall, after an attendee asked the former vice president to clarify his position on Social Security. A series of viral videos shared by Sanders speechwriter David Sirota show Biden calling for cuts to the program.

"My stance on Social Security — let’s get the record straight — I’m not gonna blame anybody, but let’s get the facts. There’s a little doctored video going around saying that, put out by of Bernie's people, and I don’t know if my staff has that video here, saying that I agreed with Paul Ryan, the former vice presidential candidate on wanting to privatize Social Security," Biden said. "And PolitiFact looked at it and doctored the photo and doctored the piece and acknowledged that it’s a fake. So what we’re doing is is putting out what the actual exchange between what Paul Ryan and I were discussing, and I’ve been a gigantic supporter of Social Security from the beginning."

"But it is a simply a lie that video that’s going around and ask anybody in the press, it’s a flat lie," he added. "They’ve acknowledged that it’s a doctored tape, and I’m looking forward to his campaign coming forward and disowning it. They haven’t done it yet."

Hours after Biden's remarks, Sanders campaign manager Faiz Shakir issued a statement calling on Biden to "be honest with voters," over his record.

"The facts are very clear: Biden not only pushed to cut Social Security — he is on tape proudly bragging about it on multiple occasions," the statement reads. "The vice president must stop dodging questions about his record, and start explaining why he has so aggressively pushed to slash one of the most significant and successful social programs in American history, which millions of Americans rely on for survival.”

Earlier this month, Sirota began tweeting and emailing links out of several news clips showing Biden praising GOP plans to curb federal entitlement programs such as Social Security. Other videos showed Biden calling for a freeze on any hikes to the program's payments.

"You have to, it's one of the things that political advisers say to me is 'Whoa, don't touch that third rail.' Look, the American people aren't stupid. It's a real simple proposition we have to do something," Biden said in a 2007 Meet the Press interview. "Social Security isn't the hard one to solve. Medicare — that is one gorilla in the room. And you've got to put it all on the table. You've got to."

PolitiFact never said the videos in question were doctored, though the website did mark as false a line in a Sanders campaign newsletter that read, "In 2018, Biden lauded Paul Ryan for proposing cuts to Social Security and Medicare."

Sanders has been in the midst of an offensive against Biden since the beginning of the year. In numerous speeches and campaign statements, Sanders has targeted Biden for his past foreign policy decisions such as the Iraq War, as well as domestic spending. Much of that strategy is thanks to the fact that polling regularly finds Biden backers most likely to pick Sanders as their second-choice candidate.

A RealClearPolitics average of recent polls out of Iowa shows Biden and Sanders in a virtual tie at 20.7% and 20.3% support, respectively.