Though they have surfaced only fleetingly in the opening rounds of the presidential campaign, some of the deepest and most explosive divisions between George W. Bush and John F. Kerry are over the future of retirement.
The issues are so politically treacherous and abstract that both candidates have shied away from them in public - an easy thing to do when the headlines have been dominated by Iraq, the 9/11 commission and jobs.

But make no mistake: a philosophical and intensely partisan war is raging just below the surface, and strategists on both sides expect that retirement issues will come into play before the campaign comes to a close. The fissures between Republicans and Democrats are deep. Trillions of dollars are potentially at stake, and powerful interest groups are already marshaling forces.

The issues range from Social Security and Medicare to the stability of private pension plans, but much of the war boils down to a basic question: should Americans save for old age collectively as a nation, or as individuals through private savings and investments?

This rift has, if anything, deepened in the last four years, even as the political ground has shifted.

Democrats hope to tie the traditional distrust many older Americans have for proposals that seem to threaten Social Security or Medicare to broader economic anxieties of younger workers about job losses, shaky pension plans, shrunken private savings, the federal deficit and cutbacks in retiree health plans.
Republicans, who usually accuse their opponents of exaggerating threats to the programs, are resorting to fear as well. They are warning that the two giant entitlement programs will be overwhelmed by soaring costs as the nation's 76 million baby boomers begin to reach retirement age in 2011.

President Bush has also worked hard to blunt the Democrats' longstanding advantage on retirement issues by winning approval for a prescription drug plan for the elderly - a huge new government entitlement program.

The gambit may not pay off. Polls show that voters are lukewarm at best toward the new law. Democrats have attacked it as a feeble measure with lucrative giveaways to pharmaceutical companies and health maintenance organizations.

Meanwhile, the Bush administration is facing an inquiry into accusations that it suppressed its own cost estimates, which showed that the new law would cost a third more than Congress had been assuming.

And both parties are girding for much bigger battles soon after the next election. Warning that Social Security is headed straight toward bankruptcy, Mr. Bush and supporters are building a case for partially replacing the old-age program with a new system of private accounts.

Trustees for the Social Security and Medicare trust funds project that the Social Security fund for old-age benefits will be out of money by 2042 and that the Medicare trust fund will be insolvent by 2019 - just 15 years from now.

"The danger is not in doing something - the danger is in avoiding the obvious," said Terry Holt, a spokesman for the Bush-Cheney election campaign. "You cannot just cling to the status quo, and people understand that."

Democrats are sounding their own alarms, accusing Republicans of trying to shred the social safety net and impoverish the elderly. 

"The Republican approach is that you have individual responsibility for maintaining your retirement, and if you are unsuccessful then you should have done better," said Representative Robert T. Matsui, Democrat of California. 
Though President Bush has refrained from any specific proposals on Social Security, advocacy groups are already mobilizing.

SocialSecurityChoice.org, a conservative group that is pushing for private savings accounts, plans to spend up to $2 million in May on television commercials that will run in Washington, D.C., and in several swing states. "This is not an issue that the Democratic leadership can demagogue on anymore," said Bob Costello, the group's president. "We are at the tipping point on this issue." 

Liberal advocacy groups are firing back. The Center on Budget and Policy Priorities, a research group in Washington, has published a stream of reports contending that projected shortfalls for Social Security have been greatly exaggerated and can be fixed by modest adjustments to future benefits or taxes.
And MoveOn.org has spent $3.5 million on media ads attacking the prescription drug law, and is prepared to pounce on other retirement issues. "We know we'll do more," said Wes Boyle, the president of the MoveOn.org Voter Fund. "There's this sense that, just as all these people are moving toward retirement, everything is up in the air."

Strategists in both parties face a starkly different landscape than they did in 2000, when George W. Bush campaigned for letting people channel some of their Social Security taxes into private savings accounts they could manage themselves.

Back then, unemployment was still at rock-bottom lows and the stock market was still near record highs. This year, many voters are anxious about unemployment, disillusioned by the collapse of the stock market and nervous about their private pension plans.

Even those who kept their jobs in the last three years saw the value of their individual retirement accounts shrink. And the bursting of the stock market bubble left pension funds at many Fortune 500 companies, the gold standard for retirement security, seriously underfinanced.

Standard & Poor's recently estimated that, even after a rebound in the stock market last year, pension plans of the 500 largest corporations are about $259 billion short of what they need.

Indeed, after months of lobbying by business leaders, Congress last Thursday wrapped up a package that will relieve businesses from federal requirements that would have forced them to shore up their pension funds with an additional $80 billion in contributions.

The White House has concentrated its most dire warnings, however, on Social Security. "The nation must act to avert a long-foreseen future crisis in the financing of its old-age retirement programs," warned the White House Council of Economic Advisers, in its 2004 Economic Report to the President.

The solution, the report continued, is to trim the future growth in Social Security benefits and then partially privatize the program by letting people divert some of their payroll contributions to private accounts.

Administration officials admit that as much as $1 trillion in "transition costs" could be needed for the switch, but argue that the new system would save money in the long run.

White House officials now avoid the word "privatization," fearing that the word conjures up fears that Democrats can exploit. But Mr. Bush clearly remains enthusiastic about the idea and is expected to make it a priority if he is re-elected.

Many opponents, however, say the administration has deliberately blurred a major difference between the prospects for Social Security and Medicare. 
Most experts agree that Medicare faces an acute financial crisis, partly because the nation's baby boomers will begin to retire en masse in 2011 and even more because medical costs have been rising much more rapidly than the overall rate of inflation.

But most analysts also agree that the problems of Social Security, which provides old-age benefits, could be addressed with fairly modest fine-tuning to future benefits or to payroll taxes. 

Peter R. Orszag, a senior fellow at the Brookings Institution and a former official in the Clinton administration, said the projected shortfall of Social Security - $3.5 trillion over the next 75 years - is barely one third the cost of making Mr. Bush's tax cuts permanent.

Blurring the distinction makes it easier to justify an overhaul for Social Security. It also glosses over an awkward fact for Republicans: the acute deficits looming for Medicare became far worse as a result of the prescription drug bill that President Bush supported and signed.

Mr. Kerry, in line with most Democratic lawmakers, has repeatedly vowed to oppose any privatization of Social Security. "Social Security is safe and sound well into the next two decades or more," he said in January. "With very minor changes, with a strong economy, the next generation will have Social Security."
But Democrats face their own dilemmas. Even modest changes to cost-of-living increases provoke howls of protest from unions and other major Democratic constituencies. Nor have Democrats come to grips with the undisputed problems that loom for Medicare.

And neither party talks much about the effects of the longstanding trend in which employers have shifted a large share of retirement responsibilities from themselves to their workers.

Today, nearly 60 percent of workers covered by an employer pension plan rely entirely on 401(k) accounts or similar savings plans for individuals. But experts warn that most Americans set aside far less money in their 401(k) plans than they will need for retirement.

The retirement savings plans of a typical American household have only about $55,000, according to Alicia H. Munnell, director of the Center for Retirement Research at Boston College. "We are watching the demise of defined-benefit plans and the growth of plans that place all the burden on the workers, but the workers are often ill-prepared to make these sophisticated choices," Ms. Munnell said. 

But whatever the debate among economists on these issues, by November the campaigns will have to find ways of boiling their arguments down to 30-second commercials. Judging by two ads already prepared, voters can expect plenty of anxiety-making appeals.

In one television commercial broadcast in battleground states by MoveOn.org in January, retired couples discussing Medicare are upended when a shadowy figure in cowboy boots marked "GWB" literally pulls the rug out from under them.

The ad prepared by SocialSecurity Choice.org is even starker. It opens with a shot of an hourglass emptying. "Time," the announcer intones, "is running out."