Liberal House Democrats appear ready to roll over on their long-stated threat to bring down a health care reform bill that doesn’t include their preferred version of a public insurance option. The development removes the gravest challenge to leaders as they prepare to rally support for a more moderate approach — one that allows the federal government to negotiate rates under the plan with health care providers instead of pegging them to Medicare. The stalemate on the issue has stymied the rollout of a final House package. But after a weeklong whip effort, Democratic leaders in the chamber have determined the so-called robust plan falls far short of the support that it needs. They are planning a 10 a.m. Thursday press conference on the West Front of the Capitol to announce their bill. Rep. Lynn Woolsey (D-Calif.), co-chairwoman of the Congressional Progressive Caucus, cautioned that her group has made no decisions about whether to support the more moderate approach pending a look at legislative language. But she echoed many others in her ranks when she signaled liberals are ready to claim victory on dragging the plan back from the dead and accept a compromise. “We will insist on making it as strong as it can possibly be,— she said, adding, “Give credit to the progressives and the robust public option group that have pulled this and pulled this and pulled this.—Leaders of the Progressive Caucus and the three ethnic caucuses are scheduled to discuss the issue Thursday in a huddle with President Barack Obama. Woolsey and Progressive Co-chairman Raúl Grijalva (D-Ariz.) suggested they would use the White House session to focus on end game and press Obama to insert himself more forcefully into the debate in favor of a public option. Grijalva said he wants the president to pledge “that he will defend a public option, that he will continue to protect the most vulnerable people, and more importantly, no triggers, none of that stuff.—Education and Labor Chairman George Miller (D-Calif.) said it had become apparent in discussions in recent days how difficult it would be to get the votes for the robust, Medicare-based plan.”People are coming to realize that it’s very tough getting to that point,” he said. But Miller tried to downplay the move to negotiated rates.”I think the issue is whether it’s going to have a public option or not,” he said. “I think that’s the test.”Miller refused to confirm, however, that a decision had been made, noting that they were still awaiting Congressional Budget Office scores expected later today. “We’re in CBO hell,” he said. Leaders were meeting Wednesday afternoon to make their final call. Steven T. Dennis contributed to this report.