PORTSMOUTH, Ohio — The system for funding Social Security is "a disgrace" because it forces young workers to pay into a program that is unlikely to benefit them in its current form, Republican presidential candidate John McCain said this week, wading into politically touchy territory.

Like many other politicians, McCain often questions the long-term viability of the government retirement program. But he raised eyebrows with an unusually harsh assessment Monday at a town-hall forum in Denver. Asked by a young woman if she is likely to receive Social Security benefits someday, McCain said it was unlikely "unless we fix it."

"Americans have got to understand that we are paying present-day retirees with the taxes paid by young workers in America today," he said. "And that's a disgrace. It's an absolute disgrace, and it's got to be fixed."

Some Democrats criticized the remarks because McCain basically was describing how Social Security has always worked. Current retiree benefits are supplied by payroll taxes from current workers.

In a conference call organized by the Democratic Party, Gerald McEntee, president of the American Federation of State, County and Municipal Employees, said Social Security has "always been pay as you go, with today's workers paying for today's retirees. What's a disgrace is that this is news to John McCain."

Because Social Security now runs a surplus, the extra money is used to pay for other government programs. But benefits will begin to outstrip Social Security tax revenues in about nine years, the program's trustees said in March. They reported that its trust fund will be depleted by 2041 unless the formula is changed.

In Denver, McCain offered no specific remedies, but said he would sit down with Democrats and Republicans to find them.

Young workers, he said, "are paying into a system that they won't receive benefits from on the present track that it's on. That's the point. I don't think it's fair. I think it's terrible."

"That's why we have to fix it," McCain said, pointing to a 1983 bipartisan agreement that bolstered Social Security for a while by cutting benefits and raising taxes.

McCain declined to say whether he would endorse a similar package, or a higher retirement age or other suggestions that have been made.

"I cannot tell you what I would do," he said, "except to put everything on the table. Because as soon as I say 'This is what would be my requirement,' then you get into a huge fight and you get all the special interests involved. I would put everything on the table."

In 2005, President Bush proposed a partial privatization of Social Security, in which some of a worker's payroll taxes would go into an investment account that would follow the worker into retirement. It proved unpopular with the public and Congress, then controlled by Republicans, set it aside.

McCain's Democratic rival, Barack Obama, has suggested a tax on high-earning workers to boost Social Security's long-term health. Currently, wages up to $102,000 a year are subject to a 12 percent payroll tax, which is evenly split between workers and their employers.