Republicans, who will control the House starting in January but will remain in the minority in the Senate, acknowledge that they do not have the votes for their ultimate goal of repealing the health law, the most polarizing of Mr. Obama’s signature initiatives.
But they said they hoped to use the power of the purse to challenge main elements of the law, forcing Democrats — especially those in the Senate who will be up for re-election in 2012 — into a series of votes to defend it.
Republican lawmakers said, for example, that they would propose limiting the money and personnel available to the Internal Revenue Service, so the agency could not aggressively enforce provisions that require people to obtain health insurance and employers to help pay for it. Under the law, individuals and employers who flout the requirements will face tax penalties.
Moreover, Republican leaders said, they plan to use spending bills to block federal insurance regulations to which they object. And they will try to limit access to government-subsidized private health plans that include coverage of abortion — one of the most contentious issues in Congressional debate over the legislation.
Those are just a few examples of the ways in which newly empowered House Republicans plan to use spending bills to pressure Mr. Obama and Senate Democrats to accept changes in the law.
Given their slim majority, Senate Democrats must stick together if they want to avoid sending Mr. Obama spending bills and other legislation that he would feel compelled to veto, setting up the prospect of a broader deadlock and, in an extreme situation, a government shutdown.
The House Republican whip, Representative Eric Cantor of Virginia, described the strategy this way: “If all of Obamacare cannot be immediately repealed, then it is my intention to begin repealing it piece by piece, blocking funding for its implementation and blocking the issuance of the regulations necessary to implement it.”
“In short,” Mr. Cantor said, “it is my intention to use every tool at our disposal to achieve full repeal of Obamacare.”
The Senate Republican leader, Mitch McConnell of Kentucky, said he, too, wanted to shut off money for the new law.
Mr. Obama has made clear that he will fight to preserve all the fundamental elements of the law. When asked if the president would veto legislation to cut off money, his spokesman, Robert Gibbs said, “I don’t think we’ll get to that.”
Both sides said they were determined to avoid a government shutdown like the one in 1995 that, by many accounts, did political damage to House Republicans and Newt Gingrich, who was then speaker.
Anticipating the Republican assault, White House officials said Mr. Obama would emphasize how the law protects consumers and gives them more control of their insurance. Administration officials are working with Senate Democrats to arrange hearings at which consumers would explain how they have already benefited from the law.
One of the president’s strongest allies is Senator Tom Harkin, Democrat of Iowa, an architect of the law. Mr. Harkin said he would “fight any attempt to defund the law or repeal its consumer protections.” He is well placed to lead such resistance. He is chairman of the Senate’s health committee and of its Appropriations subcommittee responsible for health programs.
The number and variety of restrictions Congress can impose in spending bills is almost unlimited. A bill passed by the House last year, for example, stipulated that no federal money could be used to buy light bulbs unless they met certain energy efficiency standards. The same bill said, “No funds appropriated in this act may be used for the transportation of students or teachers in order to overcome racial imbalance in any school.”
House Republicans could easily pass similar provisos stating that no federal money could be used to carry out specific sections of the new health care law.
By attaching the restrictions to appropriations bills, House Republicans can force negotiations with the Senate. The Hyde amendment, restricting the use of federal money to pay for abortion, began as such a rider more than 30 years ago.
House Republicans said their efforts were inspired, in part, by the words of Senator Robert C. Byrd, the West Virginia Democrat who died this year. Mr. Byrd described the power of the purse as “one of the most effective bulwarks ever constructed” to shackle the hands of an overreaching executive.
Even if judges uphold the constitutionality of the law, federal officials will still need money to administer and enforce it. And that is where House Republicans see an opportunity to assert their influence, with a real possibility of a stalemate.
The White House has provided money to states to help them get ready — to scrutinize increases in insurance premiums and to set up regulated markets known as insurance exchanges. In addition, the law provided $1 billion for “federal administrative expenses.” But that is far less than will be required.
The Congressional Budget Office says the Internal Revenue Service will need $5 billion to $10 billion over 10 years to determine who is eligible for tax credits and other subsidies intended to make insurance affordable. The Department of Health and Human Services will need at least that much to carry out changes in Medicaid, Medicare and the private insurance market, the budget office said.
The law provided $11 billion for community health centers to serve 20 million more low-income people, including many expected to gain coverage under the law. Many Republicans, including President George W. Bush, have supported such clinics.
But Daniel R. Hawkins Jr., senior vice president of the National Association of Community Health Centers, said, “It’s unclear how we will fare in the new climate.”
The House Republicans’ campaign manifesto proposed “strict budget caps” that would cut spending for most domestic programs subject to annual appropriations.
The conflict over health care may be the biggest obstacle to cooperation between Mr. Obama and Republicans in Congress.
“House Republicans cannot enact legislation the president won’t sign,” said R. Scott Lilly, a former Democratic staff director of the House Appropriations Committee. “But the president cannot force them to appropriate money they don’t want to appropriate.”