WASHINGTON – A budding bipartisan deal to shelter physicians from Medicare cuts, championed by the House’s two top leaders, is drawing powerful allies including the American Medical Association and a rainbow of conservative and liberal groups.

House aides released an outline of the emerging measure late Friday, and it confirmed what lawmakers, aides and lobbyists have described for days. The package is studded with provisions that draw many Democrats, including two more years of money for the Children’s Health Insurance Program and community health centers, plus language boosting Medicare costs for some beneficiaries that appeals to Republicans eager to retool the costly program’s finances.

The effort to resolve a problem that has exasperated Congress for years has been pressed by House Speaker John Boehner, R-Ohio, and Minority Leader Nancy Pelosi, D-Calif. Their rare alliance has given the proposed deal momentum among lawmakers of both parties eager to be rid of the issue.

The proposal is also attracting powerful foes and its fate is not guaranteed. A House vote seems likely late next week, shortly before Congress begins a two-week spring recess, but what will happen in the Senate is less clear.

On Saturday, all 12 Democrats on the Senate Finance Committee released a letter suggesting they might oppose the plan unless House leaders change it.

They said a package extending the children’s health program “would go a long way to achieving bipartisan support,” and listed other concerns like its increased costs for some beneficiaries.

Without those changes, “there is no guarantee” the measure will pass the Senate, they wrote.

Citing the plan’s increased Medicare premiums for high earners and other increased costs for beneficiaries, AARP – the senior citizens’ lobby – said the package “is not a balanced deal for older Americans.” With most of the measure financed with deeper federal deficits, the conservative Club for Growth urged lawmakers to vote “no” because it “falls woefully short” of being paid for.

The measure got a boost Friday from the liberal Families USA, which cited the importance of financing the children’s health program and providing for the 8 million children it serves. “Keeping the program’s funding extension is essential so we don’t move backwards,” said Ron Pollack, the group’s executive director.

Also voicing support was Robert Wah, president of the American Medical Association, who said it was time for Congress “to seize the moment and finally put in place reforms” that would end the constant threatened cuts and strengthen Medicare.

At its core, the plan would block a 21 percent cut in doctors’ Medicare fees looming April 1. It would replace a 1997 law that has threatened similar reductions for years – which Congress has repeatedly blocked – with a new formula aimed at prodding doctors to charge Medicare patients for the quality, not quantity, of care.

In a first hint of some of the measure’s fine print, Friday’s summary said it would let the government withhold 100 percent of any delinquent taxes providers owe from their Medicare reimbursements.

As for winners, the agreement would prolong federal payments to Tennessee hospitals that treat low-income people through 2025.

It would also help major producers of durable medical goods and prosthetic devices by penalizing low-ball bidders for Medicare business. That provision comes from a House-passed bill sponsored by Rep. Pat Tiberi, R-Ohio, whose state is home to Invacare Corp., one of the country’s largest makers of home medical devices like wheelchairs.

The one-page document provides no price tags and few specifics. But as lawmakers, congressional aides and lobbyists have said for days, it would cost roughly $210 billion over a decade, with around $140 billion financed by adding to federal deficits, aides said Friday. The remaining $70 billion would be split about evenly between Medicare providers and beneficiaries.

In a letter to House Democrats on Friday, Pelosi hailed the measure for “providing certainty to our seniors and stability to providers.” On Thursday, Boehner said it was a chance to “solve this problem once and for all.”

According to the summary and aides familiar with details:

 About 2 percent of the country’s highest-earning Medicare recipients would face higher premiums for doctor and prescription drug coverage. The higher premiums would apply to individuals earning between $134,000 and $214,000 and couples earning between $267,000 and $428,000.

 Starting in 2020, some people buying Medigap plans – they insure expenses Medicare does not cover – would pay higher out-of-pocket costs up to the Medicare deductible for doctors’ coverage, currently $147 annually.

 A 3.2 percent increase in Medicare payments to hospitals in 2018 would instead be phased in over six years.

 Nursing homes, hospices and home health providers would be held to a 1 percent Medicare increase in 2018.

 Scheduled cuts in payments to states for hospitals treating poor patients would be delayed a year to 2018 but also extended through 2025.

 Programs that help poor seniors pay Medicare deductibles and help some families keep Medicaid coverage as they move from welfare to jobs would become permanent.