Former Vice President Joe Biden accused Sen. Bernie Sanders (I-Vermont) of releasing a “doctored” video attacking him about Social Security, indicating mounting tensions between the two campaigns as the Iowa caucuses near.

“Let’s get the record straight,” Biden said at Simpson College in Indianola, Iowa. “There’s a little, doctored video going around … saying I agreed with Paul Ryan, the former vice presidential candidate, about wanting to privatize Social Security.”

However, the video published by the Sanders campaign was not doctored, according to Politico. The remarks in the video were his verbatim statements made to the Brookings Institution think tank in 2018. In a separate instance of the Sanders campaign criticizing Biden for his history with Social Security, they wrote in a Jan. 7 campaign email that “Biden lauded Paul Ryan for proposing cuts to Social Security and Medicare.”

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Their claims in the email were determined to be inaccurate by Poynter Institute’s Politifact, an online political fact checker.

“The Sanders campaign plucked out what Biden said about Ryan, but ignored the complete passage which showed that Biden wanted Social Security and Medicare protected, and to accomplish that goal would require making changes to the tax code,” reads the Politifact article. “The thrust of his point about the tax code was that he was saying it does too much to help the uber rich.”

Biden mixed up which claim his opponent’s campaign got wrong saying: “PolitiFact looked at it and they doctored the photo, they doctored the piece and it’s acknowledged that it’s a fake.”

There is no evidence that the video was doctored.

Sanders’s campaign manager Faiz Shakir criticized Biden in a statement Saturday for trying to cover up his former stance on Social Security.

“Joe Biden should be honest with voters and stop trying to doctor his own public record of consistently and repeatedly trying to cut Social Security,” Shakir said. “The facts are very clear: Biden not only pushed to cut Social Security — he is on tape proudly bragging about it on multiple occasions.”

Although he previously sought to cut Social Security, Biden’s current proposal calls for additional spending.

“It is simply a lie, that video that’s going around. And ask anybody in the press, it’s a flat lie. They acknowledged that,” Biden said. “This is a doctored tape. And I think it’s beneath him. And I’m looking for his campaign to come forward and disown it. But they haven’t done it yet.”

It is a very tight race between Biden and Sanders in Iowa, and both have campaigned relentlessly to secure convention delegates on Feb. 3. An Iowa polling average on RealClearPolitics from Dec. 27 to Jan. 18 shows just a 2.7 point difference between the two, with Biden leading at 21.5%.