Hernandez is charged with killing semi-professional football player Odin Lloyd, 27, of Boston. Hernandez pleaded not guilty in September to murder and five weapons charges.
Defense lawyers said Wednesday they would object to a formal request for recusal for Bristol County Superior Court Judge E. Susan Garsh, The (Fall River) Herald News reported.
Garsh set an Oct. 21 hearing on the prosecution motion.
The judge declined Wednesday to impose a gag order. Attorneys for Hernandez said the former New England Patriots tight end's right to an impartial trial has already been significantly harmed by pretrial publicity.
Prosecutors said they had instructed investigators in the case not to speak to the media and argued that early media reports on details of Odin's slaying -- and Hernandez's alleged involvement in it -- had been based on unofficial sources.
Garsh told the attorneys Massachusetts Rules of Official Conduct are a suitable alternative to a gag order, the Herald News reported.
Four others, including Hernandez's girlfriend and cousin, have been charged in the case.