With a number of Democrats and a few Republicans in Congress calling for Gonzales to step aside as the nation's chief law enforcement officer, Bush telephoned him early on Tuesday, White House spokeswoman Dana Perino said.

"The president reaffirmed his strong backing and support of the attorney general," Perino said.

Congressional committees plan to vote this week on whether to subpoena those who refuse to testify. They are particularly interested in hearing from White House political strategist Karl Rove. A former aide to Rove was named to replace one of the prosecutors fired last year.

Critics charge the administration dismissed the prosecutors to make room for its allies or because it felt some were too tough on Republicans and not tough enough on Democrats.

Recently released documents showed the administration had considered firing all the nation's 93 U.S. attorneys, each a Bush appointee, at the end of president's first term in January 2005. But later it decided to dismiss just eight.

The documents also showed the U.S. attorneys were judged on such factors as their effectiveness as well as their loyalty to the administration.

Former prosecutors said they were given little if any reason for their dismissal and were warned the administration might retaliate if they complained. The administration denied any such threats.

Many Republicans lawmakers have said publicly that no judgment should be made on Gonzales until the facts are determined.