Franks is smarting from a bruised left knee suffered while being gang-tackled after making a catch midway through the fourth quarter of last Sunday's loss to Cleveland. He has yet to practice this week and is no better than questionable to play this weekend.
The impact of not having Franks would be felt more with the Packers' struggling run game against the Buccaneers' top-rated rush defense.
"He's a bigger threat blocking than he is receiving," QB Brett Favre said Wednesday.
If Franks can't recover in time for Sunday, the Packers will be considerably thin from not only a blocking but a pass-catching standpoint at tight end. They re-signed Ben Steele on Wednesday to fortify the depth chart behind David Martin and Donald Lee.