WASHINGTON — For President Bush, the budget sent to Congress last week outlines a painful path to meeting his promise to bring down the federal budget deficit by the time he leaves office in 2009.

But for the senators and governors already jockeying to succeed him, the numbers released in recent days add up to a budgetary land mine that could blow up just as the next president moves into the Oval Office.

Congress and the White House have become adept at passing legislation with hidden long-term price tags, but those huge costs began coming into view in Bush's latest spending plan.

Even if Bush succeeds in slashing the deficit in half in four years, as he has pledged, his major policy prescriptions would leave his successor with massive financial commitments that would begin rising dramatically the year he relinquishes the White House, according to an analysis of new budget figures.

Bush's extensive tax cuts, the new Medicare prescription-drug benefit and, if it passes, his plan to redesign Social Security all balloon in cost several years from now.

His plan to partially privatize Social Security, for instance, would cost a total of $79.5 billion in the last two budgets that Bush will propose as president — and an additional $675 billion in the five years that follow. New Medicare figures likewise show the cost almost twice as high as originally estimated, largely because it will mushroom long after the Bush presidency ends.

"It's almost like you've got a budget, and you've got a shadow budget coming in behind that's a whole lot more expensive," said Philip Joyce, professor of public policy at George Washington University.

By the time the next president comes along, some analysts said, not only will there be little if any flexibility for any new initiatives, but the entire four-year term could be spent figuring out how to accommodate the long-range cost of Bush's policies.

"That president would have to face a very fundamental decision as to whether he would want to do what was right and be a one-term president or continue to play the same game and push it onto his successor," said Leon Panetta, who served as budget director and chief of staff under President Clinton.

The knowledge of what's ahead is not lost on some of those eyeing Bush's job.

"Hopefully some very difficult decisions will be addressed between now and the time we have a new White House resident so that occupant isn't faced with some very expensive chickens coming home to roost," said John Weaver, an adviser to Sen. John McCain, R-Ariz.

But Bush advisers say that his solutions will pay off in the long run.

Joshua Bolten, director of the White House Office of Management and Budget, predicted last week that making the Bush tax cuts permanent could have positive economic consequences that would mitigate their costs. And he expressed hope that the Medicare prescription-drug law might result in health-care savings not captured in the current cost estimates.

As for Social Security, Bush aides said, the president's plan would wipe out a long-term structural deficit that faces the nation in coming decades, and the transition costs in the next decade or so ultimately will be overshadowed by the benefits.

If Congress were to pass Bush's Social Security plan and permanently extend his tax cuts, the budget deficit would bottom out at $251 billion in 2008, then climb steadily to $335 billion by 2015, according to an analysis by The Washington Post and the House Budget Committee's Democratic staff.

Those figures assume, however, that Bush will secure all of his proposed spending cuts, that he will need no more emergency war spending and that there will be no changes to the alternative minimum tax, which Bush and other politicians want to rewrite to keep it from affecting more middle-class families.

The White House's own 10-year costs of the Medicare drug benefit, the president's tax cuts and the plan for private Social Security accounts are beginning to jar Republicans into rethinking the budget's trajectory, said Sen. Lindsey Graham, R-S.C.: "The days of being everything to everybody are quickly coming to a close."

The looming problems were easily foreseeable, said Joyce, the public-policy professor. The White House and Congress vowed last year to squeeze the 10-year cost of a prescription-drug bill into a $400 billion window over 10 years. But to do it, the 2004 law did not come fully into force until 2006.

Hence, legislation once priced below $400 billion over 10 years now will cost at least $724 billion over a decade, simply because the law would be fully in effect then.

Tax cuts approved in 2001 and 2003 were held to $1.7 trillion through an array of slow phase-ins, phase-outs and a Dec. 31, 2010 end date when all of the tax cuts would vanish. Now, Bush wants them made permanent, but according to White House numbers, a five-year extension beyond 2010 would cost nearly $1.1 trillion.

Likewise, Bush is proposing a Social Security restructuring that would cost $754 billion through 2015, including added interest costs for the government. But the proposal would begin slowly, with initial borrowing in 2009. The plan would be fully effective in 2011.