House liberals are keeping up their pressure on key Democrats — including President Barack Obama — and urging them to embrace a robust public insurance option. But the move comes as their own party leaders have been unable to find the votes for such a plan and have signaled they may take a more moderate approach.

The liberals say a reform plan with rates tied to Medicare instead of higher rates negotiated between the government and health care providers would save taxpayers $85 billion and would insure the most people.

And they are warning of a backlash next year at the polls if Democrats fail to deliver a robust public option that voters can afford.

But liberals are facing a behind-the-scenes effort by powerful doctor and hospital groups to nix the Medicare-linked public option and are having trouble getting the votes that they need with Obama staying on the sidelines.

Speaker Nancy Pelosi (D-Calif.) still hasn’t pulled the plug on the Medicare rates option, although she set the stage last week for using the Senate’s negotiated rates, which the Congressional Budget Office says will cost $85 billion more. Pelosi said she could argue for either.

Pelosi continued to make calls over the weekend to individual Members to gauge their support and still has not made a decision on which way to go, according to a Democratic leadership aide. Leadership will resume their discussions Tuesday morning.

Rep. Raúl Grijalva (D-Ariz.), co-chairman of the Congressional Progressive Caucus, said there is a big difference between the two plans.

“Without the robust plan, based on Medicare plus 5 [percent], there is no competition, there is no mechanism to drive down costs for insurance companies and you hurt coverage,— Grijalva said.

He’s also not in love with the “opt out,— where individual states could choose not to participate.

“My state would opt out immediately,— he said, predicting that Texas and other conservative states would as well, despite having some of the highest rates of uninsured people in the country.

“Without protections for those people who would be left behind, I would have a hard time,— Grijalva said. “The people that I represent would be out of the loop. While it has some convenience politically, what it means practically is you will be denying the public option to millions of Americans.—

Rep. Lynn Woolsey (D-Calif.), co-chairwoman of the Progressive Caucus, praised Majority Leader Harry Reid’s (D-Nev.) push for a public option as a big step forward for the bill but said the House should build on that momentum.

“Two weeks ago the Senate wasn’t even predicted to have a public option,— she said. “If they can come that far in just a few weeks, I would certainly think that the House could go for a robust public option. This is what the public wants.—

Woolsey, however, said she doesn’t think many states will opt out.

“The states that are going to opt out will have to go through their legislature, they will have to vote against covering all of their people and they will have to justify it,— she said. “I don’t think many will do that.—

Grijalva said there also is growing disappointment that Obama hasn’t picked up the phone to help Pelosi advocate for a stronger public option.

“If we are down to nine or 10 votes, I’m sure the power of that office could turn those votes around pretty quickly,— Grijalva said.

Grijalva said the public option has become symbolic for the left and represents a lot of other frustrations that voters feel as well.

“This is not just Members of Congress. Rank-and-file Democrats in the progressive wing of the Democratic Party see this as a litmus test,— he said.

“Unfulfilled expectations and cynicism keep people home, and we’re running the risk of that happening.—

House liberals have frequently warned they will bring down a bill without the “robust— plan, but Pelosi has in the past scoffed at those threats, and some Democratic aides believe she could roll enough liberals to back a more moderate bill if Obama was on board.

Complicating the leadership effort to round up support for Medicare rates last week was a quiet push by representatives for doctors and hospitals, who signaled they would oppose a bill with that reimbursement scheme. The American Medical Association has never supported a public insurance option, but as it has emerged as a certainty in the House bill, the doctor group has been intensely lobbying House Democratic leadership and members of the Blue Dog Coalition to opt for negotiated rates.

The AMA supported a measure in the House Energy and Commerce Committee health care bill that included a similar provision — along with their top priority, a $247 billion, 10-year fix to scheduled reimbursement cuts to doctors. Democrats are expected to strip that provision, the “doc fix,— from the broader bill and try to move it separately instead of scrounging for a way to pay for it in the health care overhaul. But it was soundly rejected in the Senate last week, and its path forward is anything but clear.

Health care lobbyists say that with the doc fix hanging in the balance, the reimbursement rate under the public option has become even more important to the AMA.

“We do not believe that a public option is the best way to stimulate competition among insurers,— AMA Board Chairwoman Rebecca Patchin said in a statement. “The AMA firmly believes that physicians should be able to negotiate payment rates if a new public option is created.—

Should House leadership move forward with a mandated rate, it could prove the difference between the AMA staying on the sidelines or mounting an aggressive campaign against the bill.

“There’s a big difference between muted opposition and the AMA going nuclear and creating all-out chaos,— one Democratic health care lobbyist said.

Some specialty doctors groups, including the American Society of Anesthesiologists, have already pivoted to try to get carve-outs from mandated rates.

Woolsey said the pushback from the doctors and the hospitals isn’t surprising because the lower Medicare reimbursement rates mean less pay for them and the doctor reimbursement issue hasn’t been resolved.

But Woolsey said the overall bill will be good for them because they will be getting 40 million new, paying customers instead of providing a flood of free care to the uninsured.

House Democratic leaders also continue to push Senate leaders to consider using the filibuster-busting rules, known as reconciliation, to jam a bill through if they can’t get all 60 Democrats to allow the bill to move.

House Majority Whip James Clyburn (D-S.C.) said the majority should rule, not 60 votes.

Meanwhile, a House Democratic leadership aide praised Reid for getting on board with a public option.

“Reid’s thrown down the gauntlet,— the aide said. “We’re ready to go. We just need these last few yards. … We can get there in the House.—

Tory Newmyer and Anna Palmer contributed to this report.