So far, prominent liberal interest groups have all stopped short of calling on Democratic senators to kill the current Senate health care bill. No more. circulated a petition to its members this afternoon urging liberal lawmakers to block the current bill.

The petition states: "America needs real health care reform--not a massive giveaway to the insurance companies. Senator Bernie Sanders and other progressives should block this bill until it's fixed."

"[There's enormous pressure from all sides to pass a bill quickly, no matter how weak it is. Let's show Bernie and other progressives that we're counting on them to block this version of the bill--and we'll get their backs if they do," MoveOn wrote to its supporters in the email.

Sanders (I-VT) said yesterday that, at this point, he would not vote for the Senate bill. Sanders has not made up his mind, according to a spokesman, but along with Sen. Roland Burris (D-IL) he represents liberals' best chance at getting one of their Senate allies to oppose the bill unless changes are made.