Story highlights Hillary Clinton is applying pressure to Bernie Sanders over the cost of his proposal for a single-payer health care system

The two will square off in a debate before the first voters caucus in Iowa on Feb. 1

New York (CNN) Hillary Clinton said her attacks against Bernie Sanders' health care program were "absolutely founded" because the senator wants to radically change health care in the country but has yet to provide any details.

"Basically what he is doing is saying, 'Hey, we need to start all over again, lets tear (Obamacare) up and replace it. Details to be forth coming,'" Clinton told MSNBC's "Morning Joe."

Sanders and his top campaign aides appeared to contradict each other earlier this week on when the Vermont senator -- whose recent rise in the polls has worried Clinton's campaign -- will release his sweeping Medicare-for-all, single-payer health care plan.

Jeff Weaver, Sanders campaign manager, said earlier this week that his plan, including details on how he would pay for it, would likely not come out before the Iowa caucuses on February 1. That contradicted what Sanders had told CNN the night before and the senator doubled down on his pledge to release his health care plan last night

"The truth is we already have a plan," Sanders said, referencing his 2013 proposal for expanding Medicare. He later added that the plan will be release "certainly before Iowa."

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