WASHINGTON -- An independent political group critical of U.S. Sen. Rick Santorum is raising thousands of dollars from contributors that include entertainer Barbra Streisand and media mogul Robert F.X. Sillerman, whose company owns "American Idol."

A group of Pennsylvania political operatives formed The Lantern Project last year as a tax-exempt organization known as a 527 group, and IRS filings say the group's purpose is to educate the public on issues in the 2006 elections.

Their public presence at the moment is limited to an anti-Santorum Web site known as "Santorum Exposed," but organizers say they are looking at many different ways of communicating with voters, including television ads.

Mr. Santorum, R-Pa., is seeking re-election. His likely Democratic opponent is state Treasurer Robert P. Casey Jr.

The Lantern Project's treasurer, Brian Donlen, said the group's work is not bound by the election cycle, and he described the project as "an educational endeavor" to provide information "about what we see as [Mr. Santorum's] extremism and his tendency to be hypocritical."

The fact that the Philadelphia-based group raised $328,750 before the end of last year -- 11 months before the election -- is an early sign of the prominent role 527 groups are likely to play in the next election cycle. The groups, which get their name from Section 527 of the Internal Revenue Code and are not subject to limits that are placed on donations to campaigns, raised millions of dollars to influence the 2004 presidential elections.

"Since they are perceived as being successful, I suspect we will see them pop up in a number of close races," said Larry Noble, executive director of the Center for Responsive Politics, which tracks money in campaigns. The Lantern Project's intake so far, he said, is "a fair amount of money going into an election year."

Though 527 groups may not expressly advocate the defeat or election of a candidate, they can get around that prohibition with issue ads highlighting aspects of a candidate's record. The conservative 527 group Swift Boat Veterans for Truth, for example, caused major problems for 2004 Democratic presidential candidate John F. Kerry with ads criticizing his military record.

Though some members, including Sen. John McCain, R-Ariz., had hoped to address the influence of 527 groups as part of the lobbying legislation that is before Congress, it now appears unlikely Congress will address the issue this year.

"There's a concern that [527s] may have more to say in this race than either of the candidates ... but right now they're legal," Mr. Santorum said in an interview yesterday. "Obviously we've seen in the past they're ruthless and I suspect we'll see some pretty outrageous, negative stuff coming from them."

The Lantern Project's most recent filing with the Internal Revenue Service showed that nearly a third of the money it raised last year -- $100,000 -- came from the Service Employees International Union. In the 2002 gubernatorial race, SEIU contributed hundreds of thousands of dollars to Mr. Casey's unsuccessful primary campaign against Ed Rendell.

Mr. Sillerman -- chief executive officer of the media company CKX Inc., which owns an 85 percent share of Elvis Presley Enterprises -- contributed $100,000 in November.

Nearly another third of the group's money came from the Philadelphia-based law firm Berger & Montague, and two of its top antitrust attorneys, Daniel Berger and H. Laddie Montague Jr. The firm and the two lawyers contributed a total of $100,000.

Other contributors include Ms. Streisand, who gave $2,500, and the CEO of Slim-Fast Foods, S. Daniel Abraham of West Palm Beach, who contributed $10,000. He ranked 164th in Forbes Magazine's list of the 400 richest people in America last year.

The Lantern Project paid out $70,000 in fees for fund-raising consulting last year: $15,000 went to New York-based consultant Susan Torricelli and $55,000 went to Les MacDonald, who was based in Los Angeles but is now raising funds for the group in Philadelphia.

The group's chief consultants include Celia Fischer, the former campaign manager for Democratic U.S. Senate candidate Joseph Hoeffel; Philadelphia-based Democratic consultant Doc Sweitzer; Alicia Alexion, who was treasurer of former Sen. Harris Wofford's campaign committee; and Mr. Donlen, who was Mr. Hoeffel's Web strategist.

Ms. Fischer worked on the 1986 gubernatorial campaign of Mr. Casey's father, as well as on the Pennsylvania operations of President Bill Clinton's campaign in 1992.

Last fall, Mr. Casey's campaign was critical of another independent group, Americans for Job Security, which ran ads praising Mr. Santorum's work on Social Security issues. Because that group is organized under a different section of the Internal Revenue code, as a 501(c)(6) group, it was not required to reveal its donors.

Mr. Casey's campaign did not have any comment on The Lantern Group's activities, but a spokesman said Mr. Casey believes that 527 groups should be regulated under Federal Election Commission law and be subject to contribution limits.