A Senate panel reviewed Thursday whether the Interior Department accepted donations from lobbyist Jack Abramoff's tribal clients in exchange for access to the Bush administration.

During a hearing by the Senate Indian Affairs Committee, senators grilled Italia Federici, president of the Council of Republicans for Environmental Advocacy, which Interior Secretary Gale Norton helped found.

Click to the video box at the top to watch a report by FOX News' Major Garrett.

Federici said the $500,000 given to CREA by several tribes more than three years helped do "substantive and important" work.

U.S. marshals were unable to serve Federici a subpoena for a hearing earlier this month, a situation that upset senators and set the stage for Thursday's contentious hearing. Sen. John McCain began the hearing asking Federici to swear under oath to tell the truth. McCain said he rarely swears in witnesses.

McCain, R-Ariz., asked whether the donations were part of a plot by Abramoff to use Federici to obtain access to top officials like Norton and her former deputy secretary Steven Griles.

Currently, Abramoff is the subject of five federal investigations. Among them is an indictment by a federal grand jury in Florida on charges of fraud and conspiracy in a probe about his involvement in purchasing gambling boats.

McCain has held several hearings to determine whether Abramoff and a partner defrauded six Indian tribes of some $80 million between 2001 and 2004. The senators allege some of the tribal money went to outside groups to obscure its origin.

Federici took over CREA, which Norton founded in 1999, after Norton became secretary of the Interior. The department regulates casino and environmental issues crucial to Abramoff's tribal clients.

Some e-mails between Federici and Abramoff show that Federici agreed to Abramoff's requests and asked for additional donations in the same e-mail.

"You repeatedly told Mr. Abramoff when asked that you would pass along information to, and get inside information from, the Department of Interior about issues important to this clients," McCain said. "Mr. Abramoff, and I will cite your e-mails, believed you had 'juice at the department of the Interior.'"

But Federici dismissed the e-mails.

"Senator, I get a lot of unsolicited e-mail and I'm helpful to all of my friends," Federici said.

After several unanswered questions, McCain demanded an explanation about one e-mail from Abramoff, which asked Federici to call Griles about a pending water regulation.

"You're a witness before this committee, Ms. Federici, I expect you to answer the questions. There is such a thing as contempt of Congress," McCain said.

Eventually, Federici said she couldn't remember contacting Griles. Overall, she denied doing Abramoff's bidding, attributing the flood of cash to unexpected philanthropy.

"The way you describe it in this testimony is the Indian tribes are generous, Jack is generous, everybody is generous. That is unbelievable to me," said Sen. Byron Dorgan, D-N.D.

Federici also said she frequently rebuffed Abramoff's requests and had received angry e-mails in response.

"He wasn't nearly as harsh with me as he was, say, about me," she said, quoting one particularly colorful e-mail.

The senators plan to give information they gathered relating to nonprofit groups such as Federici's to the Senate Finance Committee to investigate any abuses of their tax-exempt status.

The Associated Press contributed to this report.