The feud between Joe Biden and Sen. Bernie Sanders (D-VT) over Medicare for All is escalating, with CNN claiming the former vice president has been caught making misleading statements about the universal healthcare proposal.

Biden, who has been accused by Sanders of parroting GOP talking points to attack Medicare for All, claimed during an AARP forum in Iowa on Monday that if the proposal is implemented it will cause a gap in coverage.

“If you have these hiatuses, it may…this may go as smooth…as silk,” Biden said about the rigors of implementing Medicare for All. “But the truth of the matter is, it’s likely to be a bumpy ride getting to where we’re going. Even the people who have disagreed with my plan say, ‘Well, we’re going to have to transition three, four, five years to get there.'”

Sanders, a longtime champion of universal healthcare, responded by saying Biden’s claims were not only inaccurate, but also “preposterous.”

“It is preposterous to argue that as we expand Medicare for All that people with cancer and other illnesses will not get the care that they need,” Sanders said. However, he did not directly address how the transition to Medicare for All would work, simply saying that “over a four-year period” the program will be “expanded to cover every man, woman, and child in the country.”

CNN appeared to side with Sanders in defending the proposal from Biden’s claims that it would lead to “hiatuses” in health insurance coverage.

“To Sanders, and to us, it sounded like Biden was suggesting that Sanders’ plan would result in sick people having a gap in their insurance coverage during the transition to single-payer,” the network stated in an article fact checking the claims.

CNN reportedly consulted three healthcare experts, including one from the conservative-leaning American Enterprise Institute, that all agreed a transition to Medicare for All would “not result in people facing such breaks in their coverage.”

Biden’s team attempted to defend itself by saying the former vice president had never suggested Medicare for All would lead to gaps in insurance coverage. Instead, the campaign claimed Biden only meant “that Sanders’ plan for a sweeping overhaul of the health care system would take much longer” to be approved by Congress, thereby creating a “hiatus between the status quo and the possible future arrival of an improved system.”

The fact check comes as Sanders and Biden have found themselves on opposite sides of the healthcare debate.

Biden, who this week released his own plan centered around strengthening Obamacare by creating a public option, has alleged that Medicare for All is too ambitious and complex. The former vice president accused proponents of the plan, outside of Sanders, of not being upfront about the costs and consequences during an CNN interview earlier this month.

“Bernie’s been very honest about it. He said you’re going to have to raise taxes on the middle class. He said it’s going to end all private insurance. I mean, he’s been straightforward about it. And he’s making his case,” he said, before adding other Democrats have not been as transparent.

Sanders, for his part, has fired back by alleging that Biden is relying on the same tactics Republicans use to dismiss the plan outright. The senator expanded that criticism over the weekend, even going as far to accuse Biden of parroting Republican talking points on Medicare for All during an interview with New York Times.

“Obviously what Biden was doing,” Sanders told the Times, “is what the insurance companies and the pharmaceutical industries, Republicans, do: ignoring the fact that people will save money on their health care because they will no longer have to pay premiums or out-of-pocket expenses. They will no longer have high deductibles and high co-payments.”

“The charge that he’s making is exactly what the Republicans are saying,” he added.