Republicans "owe it to this country" to make clear what aspects of healthcare reform they would support, former Democratic National Committee Chairman Howard Dean argued Sunday.

Rebutting claims that President Obama needs to make known whether he would support a healthcare bill without his favored public (or "government-run) option for consumers, Dean insisted that it's Republicans -- not Obama -- who need to make a more concrete stance.

"I think the Republicans owe it to this country to give us a much clearer message about what they'll support, and what they won't support," Dean said during an appearance on CBS's "Face the Nation."

Dean took a shot at Sen. Chuck GrassleyCharles (Chuck) Ernest GrassleyLet Robert Mueller do his job Overnight Cybersecurity: Senators eye path forward on election security bill | Facebook isn't winning over privacy advocates | New hacks target health care Juan Williams: GOP support for Trump begins to crack MORE (R-Iowa), a key Republican negotiator of bipartisan health compromise, for saying the Obama administration had sent "mixed signals" on health reform.

"We're getting pretty mixed signals from Sen. Grassley," Dean said. "I did not hear one time Sen. Grassley say what he would vote for. When he was in Iowa all last week, he basically letting people know that he didn't think he could vote for any bill that did not get the support of his Republican caucus and Republican leadership."

Dean, a physician who no longer practices, has emerged as a vocal proponent of the public option in recent weeks as the Democratic-backed component of health reform has been under attack by Republicans during the August congressional recess.

Dean condemned the idea of healthcare cooperatives, which have been proposed by some on the FInance Committee in lieu of the public option in order to win Republican and centrist Democrats' votes.

"That proposal is a political compromise, not a policy compromise," he said. "Nobody would know what it looks like."