UPDATE: Four Five Six Fourteen more senators have signed on. Did you call yours?

I already called Arlen Specter's and Bob Casey's offices to see if they're going to sign on. Call your senators now and let them know you want them to support this last-minute push for the public option. If you don't get them tonight, call again tomorrow morning:

Four senators have signed a letter urging Senate Majority Leader Harry Reid (D-Nev.) to pass a public option for insurance coverage through the use of reconciliation.

The list of signatories includes both usual and somewhat unusual suspects, from the progressive wing of the party -- Sens. Jeff Merkley (D-Ore.), and Sherrod Brown (D-Ohio) -- to less ideological lawmakers who find themselves in primary election contests -- Sens. Michael Bennet (D-Col.) and Kirsten Gillibrand (D-N.Y.).

"Dear Leader Reid," the letter says:

We respectfully ask that you bring for a vote before the full Senate a public health insurance option under budget reconciliation rules.

There are four fundamental reasons why we support this approach - its potential for billions of dollars in cost savings; the growing need to increase competition and lower costs for the consumer; the history of using reconciliation for significant pieces of health care legislation; and the continued public support for a public option.

The petition is part of a larger effort by a coalition of progressive groups to rally Democratic lawmakers around the idea of passing a government run health insurance option through a parliamentary maneuver that would allow an up-or-down vote.

The Progressive Change Campaign Committee, Democracy for America and Credo -- a socially-conscious business -- have already secured the signatures of 119 House Democratic lawmakers for the late-stage public option push. The progressive advocacy group MoveOn.org also has emailed constituents asking them to push their representatives to co-sign the petition.