But Sen. John McCain, R-Ariz., said Wednesday the $27.5 billion the Indians are seeking in a proposed settlement is too much.
''That number is just way out of sight,'' he said at a Capitol Hill breakfast. ''We would never get the Congress to support that kind of money.''
For more than a century, McCain said, it appears the government ''never really even made any serious attempt at keeping track of the revenues'' it owed the Indians.
The Indians claim the Interior Department mismanaged oil, gas, grazing, timber and other royalties from their lands dating back to 1887. Blackfeet Indian Elouise Cobell and others filed the suit in 1996 to force the government to account for billions of dollars belonging to about 500,000 Indians.
Last month, in response to a request from McCain and others in Congress, the Indians who sued said they were willing to settle for $27.5 billion and that they had agreed on 50 principles to guide the process.
That figure is probably far less than the government actually owes the Indians, said their lawyer, Elliott Levitas.
''If you rob, burglarize the house of someone who has a lot of money, you're going to be liable for a lot of money,'' Levitas said Wednesday. ''That's what (the government) took. That's what they misappropriated. That's what they failed to account for.''
Department officials say that although some records are probably lost, they have amassed millions of pages of documentation.
''We have still a lot to do on the historical accounting, but there is a lot of documentation available,'' said Jim Cason, the department's associate deputy secretary.
The court battle has centered on whether the government can produce an accurate accounting of exactly how much it owes the Indians. The federal judge in the case, Royce Lamberth, has held both Interior Secretary Gale Norton and her Clinton administration predecessor, Bruce Babbitt, in contempt of court and has routinely criticized the department for its failure to correct problems with accounting and records.
On Tuesday, Lamberth issued a scathing decision ordering the department to acknowledge that its information about Indian trust assets might be unreliable.
''It is undeniable that Interior has failed as a trustee-delegate,'' Lamberth said.
Congress may ultimately have to decide what the Indians are owed. McCain's committee will hold a hearing in coming weeks on legislation to resolve the lawsuit.
Levitas said he thinks McCain would change his mind if he hears the Indians' stories of how their money was mismanaged and even stolen.
''We have received some criticism in Indian Country for having a figure as low as $27.5 billion,'' Levitas said.
"Based on everything they know, the number should be much higher than that.''