Sen. Bernie Sanders would not commit to supporting President Barrack Obama’s 2012 re-election bid today.

The liberal Vermont Independent, in an interview with CNN, criticized Obama’s stated desire to reform the Medicare and Social Security entitlement programs. Sanders warned that the president’s position could cost him the enthusiasm and votes of progressives.

“Absolutely,” Sanders answered, when asked if Obama has been too “wishy-washy” and willing to compromise with the Republicans.

Sanders indicated that he could see a scenario in which he does not back Obama’s re-election, saying he wants a firm commitment that entitlement programs will be protected from cuts.

“I want to hear this president tell me from his heart that he’s going to stand with working families and the middle class,” Sanders said, according to a transcript of the interview. “When he does that he will have an enormously strong support.”