The ACLU (search) withdrew Saturday from a program that allows federal workers and military personnel to contribute to charities because it requires participating nonprofit groups to check their employees' names against a government watch list of suspected terrorists.

The American Civil Liberties Union called the Combined Federal Campaign's (search) policy unconstitutional and said it would reject more than $500,000 in donations from the program rather than submit to the requirement, which was instituted under the Patriot Act, said Anthony Romero, the ACLU's executive director.

Romero withdrew the ACLU from the program and said the organization plans to sue the government over the policy. The group says the watch list is filled with errors that people listed on them have no way of correcting.

"The Patriot Act (search) and the government war on terror now threatens America's nonprofit organizations," Romero said. "We believe the new requirement violates our fundamental principles as well as the constitutional rights of our employees."

The ACLU has been an aggressive opponent of the Patriot Act, which Congress passed shortly after the Sept. 11, 2001, terrorist attacks.

The Combined Federal Campaign, which is administered by the Office of Personnel Management, the government's human resources agency, has raised millions in fund-raising drives for more than 2,000 nonprofits, including the NAACP, National Public Radio and the Alzheimer's Association. Federal employees can choose where their money is donated.

Under the new policy, groups wanting to join the program must certify they do not "knowingly employ individuals or contribute funds to organizations found" on lists of suspected terrorists compiled by the U.S. government, the United Nations and the European Union.

A message left Saturday for Mara Patermaster, the director of the charity program, was not immediately returned.

But Patermaster told The New York Times in Saturday's editions that charities and nonprofit organizations that did not check their employees' names against the federal terrorist watch list could be permanently excluded from the program.

"We expect that the charities will take affirmative action to make sure they are not supporting terrorist activities," she said. "That would specifically include inspecting the lists. To just sign a certification without corroboration would be a false certification."

The ACLU had participated in the program since 1983, but the policy's new language did not appear until the group signed an agreement extending its involvement in January, ACLU spokeswoman Emily Whitfield said.

The ACLU did not think the policy's language required it to check employees' names against the watch lists, Whitfield said.

The organization withdrew from the program after reading Patermaster's comments in the Times, Romero said. He added that the ACLU would not have participated in the program if it had known about the requirement.

"Our biggest concern is that these government watch lists are notoriously riddled with errors," Romero said. "And they allow no recourse for individuals on the list to correct those errors."

The ACLU was projected to raise about $500,000 from the program, Romero said. He spoke to the directors of several other charities and said they were also concerned about the policy.

"This is not about the money," he said. "It's about principles."