Republicans attacked the AARP (search) as well as congressional Democrats on Wednesday as they struggled to build momentum behind President Bush's call for personal investment accounts under Social Security (search).

The AARP, which claims 35 million members age 50 and over, is "against a solution that hasn't been written yet," said House Majority Leader Tom DeLay (search) after a closed-door meeting with the GOP rank and file.

He called the group's opposition to personal accounts irresponsible and hypocritical, adding that it sells mutual funds to its own membership.

In response, an AARP spokesman said the organization is "opposed to the central notion of trying to improve Social Security solvency by taking money out of Social Security."

"Even the administration has acknowledged that taking money out of Social Security does nothing to solve the solvency problem," said the spokesman, David Certner. He also said AARP encouraged its membership to invest in mutual funds "in addition to Social Security."

DeLay and Speaker Dennis Hastert also criticized congressional Democrats, who are virtually united in opposition to Bush's plans. "The party of no," Hastert called them.

Republicans unleashed their latest attack as Federal Reserve Chairman Alan Greenspan (search) urged Congress to act quickly to fix looming financing problems for Social Security as well as Medicare. "If existing promises need to be changed, those changes should be made sooner rather than later," he told the House Budget Committee.

One program provides retirement, survivors and disability income for 54 million Americans, while the other is the government's health care program for seniors.

As he has before, Greenspan endorsed a key element of Bush's plans for Social Security, a proposal that would allow workers to set aside a portion of their payroll taxes to be invested on their own. But he stressed that much more needed to be done to put the giant retirement program and Medicare, which he said faced even more severe financial strains, on a more sound footing.

Diverting the payroll taxes into the Social Security trust fund, Greenspan said, had merely allowed the government to run larger budget deficits. He said that switching to the private accounts would be a way to bolster the nation's low savings rate.

Greenspan repeated his view that a go-slow approach to setting up Bush's proposed private accounts was necessary to gauge the impact on financial markets of the increased borrowing that will be needed. "I think it is very important that you move gradually and see what the response is," he said.

"The one certainty is that the resolution of the nation's unprecedented demographic challenge will require hard choices and that the future performance of the economy will depend on those choices," Greenspan said.

Hastert and DeLay talked with reporters after meeting with lawmakers just back from a week spent sampling public opinion on Social Security. DeLay said the session produced "not one negative comment by the members."

At the same time, both he and Senate Majority Leader Bill Frist left open the possibility on Tuesday that final action may not be possible this year, and the Texas Republican conceded that opponents of Bush's plans were better organized than supporters.

Both DeLay and Hastert said Republicans are determined to move ahead with Bush's proposals, and several Republicans said they believe the president's national campaigning is slowly raising public awareness of the issue.

"We're still early in the process," said White House spokesman Scott McClellan.

Bush and congressional Republicans have consistently sought to coax Democrats into negotiations on Social Security. Democrats have just as insistently resisted, arguing that since Republicans control the White House and both houses of Congress, they must first present a comprehensive Social Security proposal of their own.

At stake is an issue of surpassing political significance. Democrats contend Bush and Republicans want to cut benefits to pay for privatizing part of the Depression-era program, and have made clear they intend to try and use the issue at the 2006 elections.

Republicans counter their goal is to shore up a program with shaky finances, but also are leery of being maneuvered into taking a series of politically difficult votes unless the result will be legislation that Bush signs and at least some Democrats support.

Bush is to travel to six states over the next two weeks, and many more later as he tries to build public support for a Social Security overhaul.

Echoing White House claims, congressional Republicans said they hope that by the time he is finished, the president will have produced a public groundswell for legislation, forcing at least some Democrats to reconsider their opposition.

Bush has said his plan would guarantee that Social Security benefits would remain unchanged for retirees and workers age 55 and over.

Younger Americans would be allowed to invest a portion of their payroll taxes on their own. In exchange they would receive a lower government benefit than they are now guaranteed, on the assumption that the proceeds of their investments would make up the difference. In addition, though, even younger voters who choose not to establish personal accounts would receive a reduced government benefit under Bush's plan, according to GOP congressional officials who have been briefed on the plan.