Republicans in both houses of Congress have said that repealing the health law is a top priority for the first months of 2017. “The Obamacare repeal resolution will be the first item up,” said the Senate majority leader, Mitch McConnell, Republican of Kentucky.
President-elect Donald J. Trump has called the law an “absolute disaster,” and has said he is eager to sign a repeal bill like one vetoed by President Obama in early 2016.
Representative Nancy Pelosi of California, the House Democratic leader, said the rules devised by House Republicans were “their opening salvo” against a law that she said had been “successful in meeting its goals of reducing cost, increasing access and improving quality of care.”
In a last-ditch bid to save his signature legislative achievement, which has provided coverage to some 20 million Americans, Mr. Obama plans to visit a meeting of House and Senate Democrats on Wednesday to rally support for the law.
The Affordable Care Act, approved in 2010 without any Republican votes, provides tax credits to help people buy private insurance. It also allowed states to expand Medicaid eligibility, with the federal government paying most of the cost for new beneficiaries.
The law also saves hundreds of billions of dollars by reducing the growth of Medicare payments to hospitals, nursing homes, health maintenance organizations and other health care providers. Repealing the law would eliminate those savings and thus increase federal spending, the Congressional Budget Office says.
The proposed rules written by House Republicans allow lawmakers to raise a point of order against legislation that causes an increase in certain types of federal spending. But the rules give special protection to bills repealing or “reforming” the Affordable Care Act, even if such bills cause a temporary increase in spending.
Republicans worry that the Congressional Budget Office could count their plan for replacing the law as new spending, making it subject to challenge on the House floor. The exception being written into House rules would help them avoid that possibility.
Ms. Pelosi pointed to this provision as evidence that the health care law, as written, saves money. In their version of the rules, she said, “Republicans are admitting that repealing the Affordable Care Act will increase costs.”
The Congressional Budget Office said in 2015 that “repealing the A.C.A. would raise federal deficits by $137 billion over the 2016-2025 period” — not only because the government would spend more on Medicare, for older Americans, but also because it would collect less in taxes from high-income households.
The 2010 law, the budget office noted, increased the payroll tax rate for many high-income taxpayers and imposed a surtax on their net investment income. The law also imposed annual fees on health insurers and manufacturers of brand-name drugs and medical devices.
Republicans may want to hold on to some of the tax revenue and Medicare savings, to help offset the cost of their plan to replace the Affordable Care Act. They have been trying to devise that replacement, but do not have a consensus and may hold hearings to examine the options.
If Congress votes to repeal the health care law early in 2017, Republican leaders say, they may delay the effective date for several years, to avoid disrupting coverage for people who have recently gained it.
The Republican rules package would also allow the House to continue its legal challenge to spending on insurance subsidies that reduce out-of-pocket costs for more than six million Americans.
In addition, the rules would require House committee chairmen to propose ways of imposing more fiscal discipline on federal entitlement programs. In the jargon of the federal budget, the goal is to switch some programs from “mandatory funding” to “discretionary appropriations,” over which Congress has greater control.
This rule mirrors ideas advanced by Representative Tom Price, Republican of Georgia and chairman of the House Budget Committee, whom Mr. Trump has selected to be his secretary of health and human services.
“Two-thirds of current expenditures are dedicated to a relatively small number of automatic spending programs like Medicare, Medicaid and Social Security, which are not subject to annual appropriations and therefore operate largely outside the control of Congress,” Mr. Price said in a recent speech.