Related: What do voters want in health care reform? Here are the talking points.

For House Majority Whip Jim Clyburn, D-S.C., a key figure who helped propel Biden into the White House, Medicaid is paramount. About 100,000 residents of his conservative state fall in the gap. "My priority is Medicaid and the coverage gap," he said.

Driving the push is Rep. Suzan DelBene, D-Wash., the leader of the 95-member New Democrat Coalition, who has urged party leaders to limit the health care provisions to ACA and Medicaid changes while leaving the expanded Medicare benefits for another day.

That isn't sitting well with Sen. Bernie Sanders, I-Vt., who has made the Medicare benefits a red line and — like every other senator in the 50-member Democratic caucus — holds a decisive vote.

"There really is something fundamentally wrong when, in the richest country in the history of the world, there are millions of seniors who have rotting teeth in their mouth, who are unable to hear what their grandchildren are saying, and study after study suggests that dementia is accelerated because people are isolated from their community because they can't hear," he told reporters. "So this to me is not negotiable. This is what the American people want."

Pelosi has said that programs will be scrapped in some cases and that expiration dates will be moved up to fit within the price range in others. Progressives see that as an invitation to fit some version of their policies in the final bill.

Senior aides say several unknowns will shape the decisions on health care. The first is where the overall spending level ends up. The second is how much the party can find in savings, which depends in large part on whether the bill allows Medicare to negotiate drug prices. Committees and policy writers are still waiting on guidance from leadership about those questions.

The ACA and Medicaid policies would cost $200 billion each, estimated Marc Goldwein, a policy expert with the nonpartisan Committee for a Responsible Federal Budget. The extra Medicare benefits would cost about $300 billion, with dental the costliest, he said, while cautioning that the numbers could change based on how they're structured. A policy for Medicare to negotiate drug prices could raise as much as $450 billion. The big question mark is centrist Sen. Kyrsten Sinema, D-Ariz., whose office has declined to confirm or deny reports that she opposes the proposal.