The 100 most prolific special-interest donors — including labor unions, trade groups and businesses — have given more than $1 billion to federal candidates and political parties over the past 14 years, a study released Tuesday found.

The American Federation of State, County and Municipal Employees and its members accounted for the biggest share of the giving, the Center for Responsive Politics found.

They contributed at least $30.6 million since the 1989-90 election cycle, with more than $9 of every $10 going to Democrats, the campaign finance watchdog group said.

More than one-fourth of the $1 billion the biggest givers poured into elections, or about $264 million, came in unlimited contributions to national party committees from corporations, unions and others. A new campaign finance law, which takes effect Nov. 6, will bar the national parties from accepting such soft money donations, allowing them instead to raise only limited contributions known as hard money from individuals and political action committees.

The Center for Responsive Politics plans to start after next month's election looking at political money raised and spent through the 2004 campaigns, executive director Larry Noble said.

"The big question now is what will the new campaign finance legislation do to all this money?'' Noble said. "Our suspicion is it will redirect a lot of it, and it will stop some of it.''

Noble noted that while the national parties will be prohibited from raising soft money, state and local party committees still will be able to raise it in states whose laws allow it. Other likely recipients of rechanneled soft money include new groups that Noble anticipates will spring up to pay for some of the get-out-the-vote activities and issue ads the national parties now finance with soft money.

In addition, some current soft money-givers may emphasize their political action committees, financed by individual contributions from members or employees, or if they do not have a PAC, simply bundle individual contributions and give them to a candidate or party all at once, Noble said.

While the new campaign finance law is aimed at eliminating soft money from federal elections, it doubles the amount an individual can give to a candidate for Congress or the White House from the current $1,000 per election to $2,000. That means President Bush, who raised more than $100 million for his 2000 primary campaign after foregoing taxpayer financing, could raise $200 million or more if he turns down public financing in 2004.

These are the top givers behind AFSCME in the center's study, and donations from them, their members and employees:

—National Education Association: at least $21 million, 95 percent to Democrats.

—National Association of Realtors: at least $20.4 million, about 53 percent to Republicans.

—Association of Trial Lawyers of America: at least $19.9 million, roughly $9 of every $10 to Democrats.

—Philip Morris: at least $18.9 million, 75 percent to Republicans.

The study didn't include multimillion-dollar individual donors, and there have been some for this fall's election as the parties wage a costly battle over control of Congress.

Hollywood entertainment executive Haim Saban, for example, has given at least $11 million to Democrats for the fall election, including a $1 million donation last month to the Democratic Senatorial Campaign Committee.