Joe Biden has called for Bernie Sanders’ presidential campaign to “disown” what he calls “doctored video” that some Sanders supporters say shows the former vice-president endorsing Republican calls to cut social security and Medicare.

“There’s a little doctored video going around … put out by one of Bernie’s people,” Biden told supporters on Saturday in Indianola, Iowa, referring to a 2018 speech in which Biden discussed then House speaker Paul Ryan saying rising deficit demanded action on the popular entitlement programs.

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“I’m looking for his campaign to come forward and disown it,” Biden continued, pointing to his 2020 campaign proposals designed to shore up social security. “But they haven’t done it yet.”

The video in question, circulated on Twitter by a top Sanders adviser, does not appear to be altered. But the short clip omits Biden’s larger argument over how Ryan handled the 2017 tax cuts and subsequent budget debates.

A separate Sanders’ adviser included a transcript of Biden’s remarks in the video clip in a separate campaign newsletter. He added other, more extended video, of Biden as a US senator in 1995 and presidential candidate in 2007 explaining his support for a more austere federal budget, including putting social security and Medicare “on the table”.

The 2020 campaign flap highlights long-standing philosophical fissures between the progressive Sanders, who has spent decades arguing for a massive expansion of the federal government, and the more centrist Biden. Those differences have come to the fore as Biden and Sanders are bunched with Pete Buttigieg and Elizabeth Warren atop early state polls weeks before the Iowa caucuses and the New Hampshire primary.

Responding to Biden’s remarks, Sanders’ campaign manager, Faiz Shakir, said: “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.

“The facts are very clear: Biden not only pushed to cut social security – he is on tape proudly bragging about it on multiple occasions,” Shakir said in a statement.

“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.”

In a 1 January tweet, Sanders adviser Warren Gunnels wrote that it “is soul-wrenching” to have heard “Biden say ‘Ryan was correct’.” He attached a 20-second video clip taken from an April 2018 speech Biden delivered at the Brookings Institution.

“Paul Ryan was correct when he did the tax code. What’s the first thing he decided we had to go after?” Biden said, leaning into the microphone. “Social security and Medicare. That’s the only way you can find room to pay for it.“

It was part of a broader speech in which Biden outlined his economic vision. He previewed his 2020 campaign emphasis on the middle class but declared that billionaires are not “the problem”, an implicit contrast with progressives.

The statement that Gunnels highlighted reflects a common Biden argument from the 2020 campaign: that Republicans pushed a tax cut whose benefits are tilted to corporations and the wealthiest Americans, knowing it would balloon the deficits, so the GOP could then justify cutting social security and Medicare.

“What I’d do is I make sure that we expand social security coverage,” Biden insisted on Friday when a voter in Iowa asked him about the program.

Biden, like most Democrats, proposes raising the cap on the level of income that is subject to the payroll taxes for social security and Medicare. That cap is set at $137,700 for the current tax year, meaning any income beyond that threshold is still subject to personal income tax, but not payroll taxes. Biden, and many other Democrats, propose lifting that cap to increase the tax revenue flowing into the Medicare and social security trust funds.

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Sanders’ camp, meanwhile, maintains that Biden’s history is more important than his current proposals. Another of their favorite video clips shows Biden, in the first years after Republicans’ 1994 midterm election romp, calling for a more austere approach.

“When I argued that we should freeze federal spending, I meant social security, as well,” Biden said at the time. “I meant Medicare and Medicaid. I meant veterans’ benefits … And I not only tried it once. I tried it twice, I tried it a third time, and I tried it a fourth time.”

Just as the Biden campaign argues that Republicans would lambaste the Vermont senator as a socialist if he wins the Democratic nomination, Sanders’ backers retort that Trump would use the same video clips they cite to harm Biden with older voters who will prove critical in battleground states in November.