

Darren Hauck for The New York Times

Republicans in the House of Representatives are poised to place a dramatic political bet.

Led by the wonkish Representative Paul Ryan of Wisconsin, they will unveil a 2012 budget on Tuesday that wagers their political futures on the assumption that voters are ready to accept tough changes in the most sacrosanct government programs.

The budget they are preparing to embrace in the coming days would slash federal government spending by more than $6 trillion over the next 10 years, mostly by reinventing the nation’s largest social programs in ways that Republicans have talked about for years.

Medicare would become a means-tested support program for private insurance. Medicaid would give states new control over their money for the poor. Taxes on business and the wealthy would come down. Overall spending across a range of programs would be capped.

In an opinion article describing the plan, Mr. Ryan calls it the “new House majority’s answer to history’s call.”

But the open question for Republicans as they approach the 2012 election cycle is whether voters will reward them for confronting those challenges even if — as has been the case in past legislative efforts of this kind — the changes they seek prove to be highly unpopular.

In the last decade, President George W. Bush abandoned plans to revamp Social Security after Democrats succeeded in convincing voters that the plan to privatize large parts of the program was a risky scheme that would inject uncertainty into a hugely popular social program.

Last year, as part of his overhaul of the nation’s health care system, President Obama succeeded in enacting a $500 billion cut to a Medicare program Democrats deemed wasteful and inefficient. In district after district across the country, Republicans hammered Democrats during the 2010 midterm elections, accusing them of taking health care away from elderly Americans.

Now, Republicans are betting that the nation’s staggering debt has created a new political dynamic — one that favors the bold over the timid and will reward the party that goes first.

Mr. Ryan and his budget team have not designed a grand bargain that would weave Republican philosophy with Democratic ideas, like a permanent end to the Bush-era tax cuts, or proposals that might make Republicans queasy, like deep cuts to defense.

Rather, Mr. Ryan and Speaker John A. Boehner appear to have calculated that Republicans hold the upper hand politically, and that by going first they can set the terms of debate over how to handle the debt. Packaging long-held Republican ideas into a huge shift in policy, the lawmakers are betting that voters will focus less on the individual things they don’t like and more on the overall impression of the party’s fiscal discipline.

Will that work? Here is a quick political rundown on a few of the most controversial proposals:

* Medicare. One of the most popular of entitlement programs, the health care system for the elderly has a rapidly growing constituency that is highly suspicious of politicians. In his article Tuesday, Mr. Ryan insisted that “its reforms will not affect those in or near retirement in any way.” But critics in the other party — and most likely some in his own — are sure to raise the specter of increased costs for those who live on fixed incomes.

* Medicaid. The Republican budget embraces the party’s long-held belief in giving states more control over the program by giving them a lump sum of money for poor patients and letting them decide how to allocate it. Critics will say it will shift costs to the states and to the individual patients and reduce access to care. Democrats have fought the idea fiercely in the past, and are likely to do so again.

* Spending. Mr. Ryan’s budget proposal would roll back spending to 2008 levels and freeze it, though not for defense — a favorite of conservatives. The plan would also impose real caps on future government spending, a move he said would “make sure government spends and taxes only as much as it needs.” The spending cuts are likely to trigger outrage from many quarters, giving ammunition to campaign opponents.

* Tax reform. The Republican plan calls for far lower corporate and individual tax rates as part of an overhaul of the tax code. But the move comes on the heels of fresh outrage over evidence that some giant corporations pay little federal tax on huge profits. And Democrats are already gearing up for a new fight over the Bush tax cuts, which they agreed to extend last year.