An organizer for liberal House Democrats says the bloc “isn’t bluffing— as it prepares to take a reputation-defining stand to protect a public insurance option in the health care overhaul.Darcy Burner, executive director of the American Progressive Caucus Policy Foundation, said the health care debate has rallied traditionally disparate Congressional liberals to hang together, while galvanizing support for their position from an array of left-leaning outside groups. The result, she said, is that Democratic leaders will not be able to clear a package through the House if it does not include the public plan.“We have never had the Progressive Caucus organized the way it is right now,— Burner said during a Friday roundtable with Roll Call. “This is not the normal scenario. And Speaker [Nancy] Pelosi [D-Calif.] knows it.—The public insurance provision has sparked a game of rhetorical chicken between, on the one hand, liberals who have pegged it as essential and, on the other, moderate Democrats and some White House officials, who have called it a deal-killer in the Senate and diminished its importance to broader reform.As an unusually contentious public debate over the reform drive has put Democrats on the defensive over the August recess, liberal leaders have been upping the ante on the public plan to beat back a building perception it would end up getting scrapped in conference negotiations.Burner said liberals have new organizational muscle to back up their threat. As evidence, she pointed to a fundraising effort coordinated by MoveOn.org and left-wing bloggers that netted about $400,000 in small-dollar donations in just a few days for 60 members of the Congressional Progressive Caucus. Those lawmakers signed an Aug. 17 letter to Health and Human Services Secretary Kathleen Sebelius pledging to vote against a bill that doesn’t include a robust public plan.A twice-failed candidate for Washington’s 8th district seat, Burner joined the caucus’s foundation in April to coordinate just those kinds of campaigns. She said she saw a gap between liberal lawmakers and what should be a ready-made base for them in likeminded grass-roots organizations that were too narrowly focused on electoral politics instead of governing. An early experiment this spring confirmed for her the potential power of the linkage. She solicited the net roots for questions to put to Progressives that they would answer on the House floor, live on C-SPAN, during the group’s weekly “special orders— session on Thursday nights. Burner said she expected a couple thousand people to participate, but in the first four weeks, 60,000 people weighed in.Burner said her group is taking other steps to help the caucus sell its position. She is in the process of establishing a political action committee that would support vulnerable incumbent members of the group and screen candidates who could join if successful. And in what will become a typical service, Burner and her still shoe-string staff put together a recess packet for Progressives highlighting the best polling analysis and messaging advice from outside groups.The group’s organizational strength faces its most serious test this fall, and Burner acknowledged it is incumbent on liberals to convince the White House it will have an easier time getting a bill through the Senate with a public insurance option than getting one through the House without one.“If Progressives aren’t willing to do the work to make the president do the right thing, it’s unlikely he will,— she said.