Federal authorities are planning to move the trial of the alleged gunman in the Jan. 8 mass shooting in Tucson to San Diego because of extensive pretrial publicity in Arizona, federal law enforcement sources said Sunday night.

Jared Lee Loughner, 22, is charged in federal court in Arizona, but court officials plan to move the case out of the state within several weeks, the sources said. They cited publicity and the sensitivity of the case in Arizona, where one of those fatally shot was John M. Roll, the state's chief federal judge.

The new chief judge, Roslyn O. Silver, will make the final decision about any venue change, but one law enforcement official said, "It's going to happen. It's just a matter of time.''

Loughner is charged in the massacre that killed Roll and five others and wounded Rep. Gabrielle Giffords (D-Ariz) and 13 others. Legal experts have said that his lawyers are likely to seek a change of venue to ensure he receives a fair trial.

Federal officials said San Diego would get the case in part because it is one of the closest judicial districts to Arizona. A San Diego-based federal judge, Larry A. Burns, was appointed last week to hear the case because Arizona judges recused themselves. Judy Clarke, Loughner's attorney, is also based there.

Although changes of venue are not regularly granted, they have occurred in high-profile cases. In 1996, for example, a federal judge moved the Oklahoma City bombing case to Denver, saying defendants Timothy J. McVeigh and Terry L. Nichols had been "demonized" in the media.

Loughner, who is charged with murder and attempted murder, is being held at the Federal Correctional Institution, a medium-security prison outside Phoenix.

For his own safety, officials said, he is being kept away from other prisoners and spends 23 hours a day alone in his cell. He gets about an hour a day to shower and exercise.