Sen. Joe Lieberman (ID-Conn.) is coming under fire from liberals upset with his promise to filibuster any Senate health care reform bill that includes a public health insurance option, but it’s unclear how much support they have for punishing the Independent Democrat.

In an e-mail Monday, activists for Democrats.com called on Senate Majority Leader Harry Reid (D-Nev.), Majority Whip Dick Durbin (D-Ill.), and Democratic Conference Vice Chairman Chuck Schumer (N.Y.) to strip Lieberman of his chairmanship of the Homeland Security and Governmental Affairs Committee.

The Democratic Conference voted last November to allow Lieberman to retain his gavel, despite his aggressive campaigning for GOP presidential candidate Sen. John McCain (Ariz.) against now-President Barack Obama.

Given Lieberman’s repeated assertions that he will vote to block any public insurance option on the Senate floor, activists seized on Reid’s comments last year that Lieberman should keep his chairmanship because “he’s with us on everything but the war.—

“Now is the time for Senate Democratic leadership — Senators Reid, Schumer, and Durbin — to stop making excuses for Joe Lieberman,— the e-mail petition states. “Harry Reid has shown great leadership in writing a health care bill that includes the public option. But Joe Lieberman is not ‘with us’ on everything but the war. Joe Lieberman’s position is against Senate Democrats, against his constituents in Connecticut and against the will of the American public. Actions must have consequences. Any senator who filibusters the public option does not deserve a chairmanship and should be removed from his or her post.—

The online petition had attracted no supporters, however, four hours after it was posted at 2 p.m.

The Democratic Conference is 60 Members strong — including Lieberman — and Reid will likely need all those votes to get a bill with the public insurance option off the Senate floor. Republicans are unanimously opposed, and 60 votes are needed to overcome a filibuster.