WASHINGTON -- Even before settling on a proposal to privatize part of Social Security, President Bush is mounting an aggressive campaign to convince the public of something that many Democrats and economists say is mistaken: that the massive government retirement system is hurtling toward disaster.

Three times in the past week, Bush has created or used public relations events to promote his view that Social Security is facing a dire financial threat and needs major repairs. Most recently, Bush said in his weekly radio address Saturday that "the system is headed towards bankruptcy down the road. If we do not act soon, Social Security will not be there for our children and grandchildren."

The issue will also be central to a White House conference scheduled for today and tomorrow meant to draw attention to Bush's economic agenda for the next four years. The public relations campaign shows that even before Congress and the public debate various plans to overhaul the hugely popular program, a major battle over Social Security is already under way.

President Bush, as one of the legacies of his presidency, wants workers to be able to shift some of their Social Security taxes into privately owned accounts, which they would invest in the stock or bond markets. In this vision, the government could pare back the benefits promised under Social Security, shoring up the finances of the program, because the return on the investments in the private accounts would help workers support a comfortable retirement.

But Bush's critics say he is overstating the financial problems of Social Security so that the public will more readily accept the "radical" cure of private accounts. Some of these critics worry that they are already running second in the public relations race.

Dean Baker, co-director of the Center for Economic and Policy Research, warns of "an incredible misunderstanding of the basic problem. The public thinks the program will disappear in 10 to 20 years."

Critics of private accounts point out that the board that oversees Social Security estimates that the program will not run out of funds until 2042 -- and even then, ongoing payroll taxes will be able to foot the bill for about 75 percent of full benefits. That leaves plenty of time, they say, to assure Social Security's future with just a little nipping and tucking -- slightly higher taxes, minimally smaller benefit increases, maybe a higher retirement age.

"Social Security is not in crisis, and the financial challenges facing the system are manageable," said Rep. Robert T. Matsui of California, the senior Democrat on the House Social Security subcommittee.

Matsui and other opponents of private accounts argue that every dollar contributed to the investment accounts would no longer be available to pay the standard benefits of workers who are now retired or soon will be.

The shortfall could run into the trillions of dollars, which the government would have to borrow, adding to the deficit.

"My generation has been told by politicians every election cycle that Social Security is going bankrupt, and we believe it," said Ben Ferguson, 23, host of a conservative radio talk show syndicated by Radio America. If there is not going to be any Social Security for members of his generation, he said, they may as well gamble with investment accounts that they control.

Bush or the Democrats: Who is right about Social Security's future? Whichever side can make the more convincing case will probably have a big advantage in the fight to determine the program's fate.