House Democratic leaders sounded bullish Wednesday after launching an all-hands-on-deck effort to win support for a “robust— public insurance option in their health care bill.

“We think we have the votes now,— Democratic Caucus Chairman John Larson (Conn.) told reporters. “We have the votes to pass a robust public option.—

Larson cautioned that the details were still being worked out, and Democratic aides said Members were still being whipped at press time and did not release a tally.

Speaker Nancy Pelosi (D-Calif.) has asked her Members to line up behind the Medicare-based plan, rather than one that negotiates rates with providers, because it saves the most money, according to the Congressional Budget Office.

“The Members understand the choices that we have to make,— Pelosi said. “If you have one option that saves $110 billion and another that saves $25 billion, how do you make up the sum of that difference?—

Leaders also have worked to tweak the proposal to appeal to Members concerned about regional disparities in part by providing an extra $8 billion in funding for states with high-quality health care outcomes and low costs, Members said, while leaders were touting a score under $900 billion from the CBO for the insurance portion of the bill.

But even with leaders increasingly confident that they have the votes to pass such a plan, they acknowledged there is still plenty of work to do on other controversial parts of the bill, and a number of Members continue to express concern about the bill’s long-term costs.

“We were surveying Members on one aspect of the bill,— one Democratic leadership aide noted. “We still have many steps ahead.—

House Democrats hope to nail down support for the public option this week, negotiate the remaining details next week and put the bill on the floor as early as the first week in November. Pelosi reiterated that she hopes a bill is sent to President Barack Obama’s desk by Thanksgiving.

Rep. Jason Altmire (D-Pa.) said he is one of a number of Members who don’t oppose the public option but will still oppose the bill unless other changes are made.

“I don’t have a problem with the public option, but I have a big problem with the bill,— Altmire said.

Altmire said he opposes the bill’s tax increase on the wealthy and mandates on small businesses.

Other Members, such as Rep. Earl Pomeroy (D-N.D.), remain hard “no— votes over tying the public option to Medicare rates, which in his state are among the lowest in the country. Pomeroy said the issue reminds him of the vote on an ill-fated British thermal unit energy tax he faced as a freshman Member of Congress in President Bill Clinton’s first term.

“I don’t see any way that a robust public option survives conference committee,— Pomeroy said. He added that increasing the eligibility for Medicaid would have saved a similar amount of money and would have won his support.

Rep. Jim Matheson (D-Utah), co-chairman of the fiscally conservative Blue Dog Coalition, said the proposal for a robust public option tied to Medicare rates was causing “a lot of concern,— and said he wasn’t sure where leadership would find the votes. Matheson said that just 12 of the 52 Blue Dogs in the past had committed to supporting such a plan.

Matheson also took issue with Pelosi’s contention that the robust plan saves the most money.

“It’s a false choice to say that the only cost issue we can talk about is the [shape] of the public option,— Matheson said. He said subsidies for buying insurance could be trimmed instead.

And he said Members wanted to see a detailed CBO analysis before committing one way or the other. “We keep hearing rumors. Let’s see it,— he said.

“We really have no details,— complained Rep. Jim Cooper (D-Tenn.), another Blue Dog. Cooper, who supports some versions of the public option, said he wants to expand the pool of Americans allowed to choose it. Under the existing bills, only about 10 percent of Americans would be included in the health insurance exchange — largely people who do not have insurance now.

“That’s a pretty small group,— Cooper said. “We should be talking about a robust exchange at the same time we’re talking about a robust public option.—