Mickelson said Tuesday night at Torrey Pines, where he is renovating a golf course, he has withdrawn his interest in his hometown baseball club, U-T San Diego reported.
"I think to be involved with the Padres you have to be fully committed to the long term," Mickelson said. "I've been born and raised here, but at this moment I'm not able to make that kind of long-term commitment to the city and to the team."
Mickelson said he let the Padres group know he was pulling out "within the last six weeks."
The ownership group includes members of the O'Malley family that used to own the Los Angeles Dodgers and local businessman Ron Fowler.
The newspaper said it was unclear what specifically led Mickelson to decide he couldn't make the commitment.