The largest independent organization opposing President Bush’s plan to add private accounts to Social Security is struggling to raise dollars from individual contributors, sources say.

Americans United to Protect Social Security has not received a single large-dollar donation from an individual since it was formed in February. Instead, the group is subsisting largely on contributions from organized labor, which has exceeded its expected level of giving, and other liberal interest groups.

As a 501(c)(4) group, Americans United does not have to publicly disclose its donors, but several sources familiar with the organization confirmed its current financial standing.

“There are peaks and valleys in any issue campaign,” said Brad Woodhouse, a spokesman for Americans United to Protect Social Security.

Woodhouse added that the group is running grass-roots campaigns in 34 states and will have the resources to continue to do so.

He predicted that once the fight over filibustering judicial nominees concludes in the Senate, donors will “recognize Social Security is the dominant issue on the legislative calendar.”

Attempting to grease the financial machinery for Americans United, Senate Minority Leader Harry Reid (D-Nev.) and House Minority Leader Nancy Pelosi (D-Calif.) have recently stepped up their outreach to donors.

In meetings over the past week, critics of the Bush plan saw some positive movement toward encouraging donations from wealthy individuals, sources familiar with the discussions said.

Regardless of future financial developments, however, dollars for the Social Security campaign have been scarce from the small group of major donors who financed America Coming Together and the Media Fund — two soft-money organizations that raised better than $200 million for the 2004 election.

Most of those givers — including billionaire financier George Soros and insurance company executive Peter Lewis — appear to be proceeding cautiously so far this cycle as they strategize about where best to spend their money.

“The big guys haven’t made their decisions about what their priorities are and where they are spending money,” said one Democratic strategist. “Everybody is stuck.”

Rob Stein, president of the Democracy Alliance — a group now being formed to facilitate the political interests of large donors — said that the idea of a conglomerate of wealthy individuals strategizing about where and when to give is misguided.

“Every donor makes judgments about his or her own giving,” Stein said “and conversations about donor collaboration, which are going on everywhere these days, are unlikely to change that anytime soon.”

Moreover, most large-dollar donations by individuals tend to revolve around a candidate rather than an issue, fundraising specialists say.

A perfect example is President Bush, whose 2004 campaign inspired a number of wealthy progressives to pour millions into a coordinated attempt to defeat him. The fight over how best to overhaul Social Security may not carry the same type of allure for many donors.

“The type of people who contribute to these things are more motivated by [judicial nominations],” said one party strategist familiar with world of big-dollar givers. “Social Security checks are not something that motivates them to get involved in the system.”

Americans United may also be a victim of its own apparent success, as wealthy donors privately calculate the anti-privatization forces have already won the battle.

“They are in the second inning of a game and everyone thinks its over,” said one Democratic strategist.

Public polling shows voters generally oppose the idea of carving out private investment accounts within Social Security — a sentiment furthered by rallies and town hall meetings around the country sponsored by Americans United as well as television ads attacking the President’s plan paid for by ProtectYourCheck.org.

Yet despite the unified opposition of the anti-privatization forces, Bush and Congressional Republicans have shown no signs of backing down on Social Security as of yet.

Ways and Means Committee Chairman Bill Thomas (Calif.) has said he will produce a bill by mid-summer and has expressed support for private accounts as well as “progressive indexing” — the two largest planks of the president’s proposal.

On the other side of the Capitol, Iowa Sen. Chuck Grassley (R) plans to hold another hearing later this month before writing a bill of his own.

“Anyone in the center-left coalition that thinks this is over needs look no farther than Bill Thomas chairing the Ways and Means Committee hearing this week,” Woodhouse said. “We are going to have to fight tooth and nail to prevent the privatization of Social Security.”