Multiple sources familiar with the situation said Detroit Lions quarterbacks coach Scot Loeffler is a strong leading candidate to join Florida's staff after the national championship game.
Loeffler is also a former Michigan quarterbacks coach. Florida coach Urban Meyer has already announced offensive line coach Steve Addazio will become Florida's next offensive coordinator.
As offensive coordinator at Florida, Mullen has had a close relationship with Tim Tebow and is also his position coach.
Loeffler has already talked to Tebow, who has said Mullen's departure could play a role in deciding if he enters the NFL draft.
Joe Schad covers college football for ESPN.