Among the reasons cited were the pre-trial publicity that the shooting has received in Arizona, which could compromise the objectivity of potential jurors.  Loughner's lawyers are said to be requesting the move in order to ensure a fair trial.

One anonymous law enforcement official involved with the trial preparations said that the move is "going to happen. It's just a matter of time."

The death of Arizona's chief federal judge, John M. Roll, at the shooting has also made a trial in Arizona particularly sensitive.  Reports the Washington Post:

Federal officials said San Diego would get the case in part because it's 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.

A final decision is expected in a few weeks' time.

Reach Executive Producer Mary Slosson here.  Follow her on Twitter here.