A report by a key U.S. Senate committee says several influential tax-exempt, nonprofit groups had improper financial ties with disgraced Republican lobbyist Jack Abramoff.
Investigators with the Senate Finance Committee say the groups took donations from Abramoff's clients, in exchange for writing newspaper columns and opinion articles favorable to his clients' positions.
The report says the organizations "appear to have perpetrated a fraud" on American taxpayers.
Among the nonprofit groups cited in the report is Americans for Tax Reform. The group was founded by Grover Norquist, a prominent conservative activist with strong ties to the Bush administration.
An attorney for Norquist told investigators that Americans for Tax Reform had not abused its tax-exempt status.
The probe was conducted by opposition Democratic Party investigators on the committee and authorized by the Republican Party chairman Charles Grassley of Iowa.
Abramoff pleaded guilty in January on charges of conspiring to bribe congressional lawmakers, including former House Republican leader Tom DeLay.
Another lawmaker, Ohio Republican Bob Ney, has pleaded guilty in connection to the investigation. He is scheduled to appear before a federal judge Friday in Washington.
Some information for this report was provided by AP .