Vikings coach Brad Childress would not confirm or deny Favre's status with the team and called it a "fluid situation." He told reporters after Tuesday morning practice that he had not heard from Favre directly about the decision.
"I'm not a big hearsay person," Childress said. "I gotta hear it from the horse's mouth."
Favre told the Vikings in 2009 that he wouldn't play for them, but he ultimately changed his mind and ended up joining the team.
Favre injured his ankle in the NFC championship, which the Vikings lost to the New Orleans Saints.
If Favre doesn't play this season - and if he decides to actually retire for good - it will end one of the most storied careers in NFL history. A three-time league MVP (1995-97), Favre won the Super Bowl in 1997 with the Packers. His 11 Pro Bowl appearances are the most ever by a quarterback.
AP contributed to this report.