When the Bush administration proposed a new Medicaid regulation last year to reduce payments to public hospitals, it seemed like just one more obscure Federal Register rule. But for John W. Bluford III, the regulation had a price tag: up to $37 million.

That’s how much annual revenue the Truman Medical Centers in Kansas City, Mo., stood to lose, accountants told Bluford, the president and chief executive of the hospital system. Weighed against an annual budget of about $420 million, “that cuts to the bone,” Bluford said.

The potential for such cuts has prompted public hospitals to lobby hard against the Medicaid regulation changes, and their efforts so far appear to have been highly effective. A bill to quash the hospital payment change, as well as six others, sailed through the House late last month with an overwhelming majority that included a host of Republicans.

Whether that pressure will have the same effect in the Senate is unclear. Majority Leader Harry Reid, D-Nev., has not decided whether to file a cloture petition to break a GOP filibuster against the bill, and Republicans believe the measure will be added to the supplemental war spending bill, perhaps as soon as this week. A number of Senate Republicans oppose the administration’s regulations as well.

The conflict over the Medicaid regulations offers several lessons in Washington politics: Even obscure Medicaid regulatory issues can become local ones; entitlements are sacrosanct; and an administration ­aiming to cut funding to hallowed public institutions like hospitals would do well to coordinate with its congressional allies first.

Several House Republicans said heavy lobbying by public hospitals combined with administration missteps led to the 349-62 vote two weeks ago in favor of the bill to postpone the changes (HR 5613).

Just 62 out of 198 Republicans voted against the bill, the rest defying their leadership and the president. Among them were stalwart conservatives like Joe L. Barton of Texas, the senior Republican on the Energy and Commerce Committee.

“I’m a strong supporter of the administration,” Barton said. “But I think Congress has a role to play, and I think generally, when you do things in a cooperative fashion, you get a better result.”

But Barton said the administration’s Medicaid regulations “were developed purely in the bureaucracy of CMS,” the Centers for Medicare and Medicaid Services, without congressional input.

The regulations would eliminate or curtail federal reimbursement for a range of Medicaid services, including busing Medicaid­-eligible children to school and providing case management services to Medicaid patients. Two of the rules would eliminate federal Medicaid funding for interns and residents at hospitals and limit the amounts that public hospitals could be paid for Medicaid services.

Medicaid is jointly funded by states and the federal government, and the new rules are part of a long dispute over which side should pay more. The federal government expects to pay about 57 percent of the costs of Medicaid in fiscal 2008, a sum that will total about $204 billion.

Together, the seven new regulations that would be postponed by the House-passed bill would shave about $17.8 billion from federal Medicaid spending over five years, according to the Congressional Budget Office.

Administration officials have said the new rules are aimed at ending federal payment for services they don’t think Medicaid should cover and curtailing abuses in the system.

The regulation affecting public hospitals first appeared as a legislative proposal in early 2006, in Bush’s fiscal 2007 budget, said Larry S. Gage, president of the National Association of Public Hospitals. After Congress ignored it, the administration proposed it as a regulation early in 2007. Gage and his small trade association — it has about 100 members, and a staff of about 30 — made stopping the new rule their priority.

“This is life and death to enough of our members, if this were implemented the way we think it would be implemented, that we pretty much had to put everything on a back burner,” said Gage.

Gage and his association assembled a coalition of like-minded groups to combat the regulation, including the larger American Hospital Association and the Association of American Medical Colleges. They won a one-year moratorium on the rule in an emergency war spending bill Congress passed last May (PL 110-28).

But Gage and his allies realized they would need a strong argument against the regulation by the time the moratorium lifted. In the meantime, the administration had started issuing the other regulations.

That was where executives of large public hospitals, like Bluford, stepped in. A large proportion of public hospital patients are either on Medicaid or aren’t insured at all, making government payments a cornerstone of their revenue.

Medicaid payments, he said, account for about 55 percent of Truman’s budget.

“We brought our members to town as often as we could,” Gage said. Bluford met in March with both of his state’s senators, Republican Christopher S. Bond and Democrat Claire McCaskill. He also led a delegation of public hospital executives to meet with the House Democratic whip, James E. Clyburn of South Carolina, the same month. House Energy and Commerce Chairman John D. Dingell, D-Mich., introduced the bill to block the regulations on March 13.

“One of the messages that I hoped resonated with our delegation is that hospitals such as ours are major economic drivers in the local community,” Bluford said.

Gage found that some of his most effective messengers were members of the boards of the hospitals, who in states like Florida were appointed by Republican governors.

“So they’re very strong, solid Republican local officials who could go to their peers,” he said.

The message began to sink in.

“Those hospitals were facing millions of dollars in a loss of revenue,” said Rep. Nathan Deal, R-Ga.

Deal supported the bill to postpone the regulations when it was approved by the Energy and Commerce Committee, but voted against it on the floor because he didn’t like the procedure Democrats used to pass it, he said.

As hospitals lobbied, the administration was not helping itself, Republicans say.

“If we’re going to be asked to take tough votes against children’s hospitals in our district, I think we’re owed an explanation,” said Rep. Michael C. Burgess, R-Texas.

Christina Pearson, a spokeswoman for Health and Human Services Secretary Michael O. Leavitt, said in a statement that “there have been multiple engagements with members and staff on these Medicaid regulations from the top of the department on down to staff level.”

The administration, realizing that lobbying by public hospitals sank not just one regulation but all seven, responded to the House vote with an olive branch: Leavitt offered to unilaterally postpone the two regulations on public hospitals and graduate students if Congress let the other five take effect. Democrats aren’t interested.

“The House has made its position clear,” said a spokeswoman for the Energy and Commerce Committee.

The Senate, of course, has not. Reid tried to pass the bill by voice vote April 29, but Tom Coburn, R-Okla., objected. A busy Senate schedule in the coming weeks may not allow the time needed for Reid to debate and pass the bill.

That’s why Republicans believe the Medicaid measure will ultimately be tacked onto the supplemental bill for war spending. No one is willing to speculate beyond that.

But many are betting that one way or another, Bluford’s hospital system will get to keep its $37 million.