The quarterback was able to work with the team yesterday, having been kept off the practice field earlier this week with a rib injury.
The head coach told reporters: "We're trying to hold out to see if Thad will be ready. We feel that if he is, we have the option to play him if he's healthy enough for us to win.
"When you're dealing with muscle injuries, they kind of take it all the way up until game time. This one's a pain tolerance situation to see what he can do.
"It's a point of the soreness in the ribs, just being able to turn and throw. That's the one thing that's holding him back is being able to turn his torso and throw. That's it. If he can get by that, he'll be able to play."
The Bills face the Kansas City Chiefs tomorrow.