President Bush has grabbed the third rail of American politics, and he isn't letting go. During last year's presidential campaign, he repeatedly warned Americans that Social Security is in a crisis and needs to be fixed soon.

The president promised to let Americans invest a portion of their payroll taxes in personal retirement accounts (PRAs) that they -- the taxpayers -- would control. It's a sensible first step. And the president is correct. Reform is necessary.

Over the next 75 years, Social Security is scheduled to pay out $27 trillion more in benefits than it will take in through payroll taxes. PRAs would close that gap. Without them we'll have to raise taxes or slash benefits -- or both -- to keep the program going.

Of course, there are some who still deny the country faces a problem. "The system is not in crisis; it has money to last for about the next half century, and even then, if nothing is done the required benefit cuts would still leave retirees better off than those getting benefits today," the Minneapolis Star-Tribune wrote in a recent editorial.

Unfortunately, that assumes that Social Security can really rely on its trust fund to pay benefits. There are billions of dollars worth of IOUs in that fund, but no real money. So, in 2018 when the program starts spending more in benefits than it takes in through taxes, the government will still need to increase taxes or cut spending in order to pay those IOUs out of general revenues.

Others argue that some relatively simple fixes today could solve the problem. A former member of President Clinton's Council of Economic Advisors sounds this theme. "Social Security does not confront a crisis," Laura D'Andrea Tyson wrote recently in BusinessWeek. "In fact, its solvency for future generations can be ensured through modest benefit reductions and modest revenue increases."

Well, Congress isn't likely to be eager to allow any reduction in Social Security benefits. It will always be easier to borrow more money instead. So let's focus on Tyson's second suggestion: Increase taxes.

In its most recent report, Social Security's Trustees estimated that increasing payroll taxes by 1.89 percentage points would put the program's Age, Survivors and Disability program on solid footing for the next 75 years.

That may seem like a small price to pay, but a recent study by The Heritage Foundation's William Beach and Rea Hederman suggests otherwise. They ran the numbers for a worker who earns $35,000 per year. For this person, that adds up to $662 each year. That's enough to buy three months' worth of gasoline, or a months' worth of groceries for the worker and his spouse.

This proposal is being billed as a small change, but it's clearly one that would put a big dent in the average family budget. Worse, for the time being, it wouldn't even work.

Remember, Social Security is currently taking in more than it spends, and it will keep doing so until 2018. So even if we increase the surplus going to the trust fund today, it doesn't matter. The government can't simply store up a pile of cash in a bank account. It will just use the extra money to buy even more government bonds, and it will spend the money to build roads, fund Medicare and pay bureaucrats.

The only way to allow any tax money to pile up is to invest it in personal accounts -- PRAs. So we're right back where we started.

People understand that we need to make Social Security an ownership program if it's going to survive in the 21st century. The president's plan to allow PRAs would do just that. Maybe that's why touching the "third rail" is no longer political suicide.

Ed Feulner, president of the Heritage Foundation (heritage.org), a conservative think tank based in Washington.