Smith (back) won't participate in Thursday's practice, Eric Smith of the Vikings' official site reports.
Though Smith is at the Vikings' facility, he'll be working out off to the side for a second straight day while he manages the back injury. The Vikings will wait and see if he's able to do anything Friday before ruling on his status for Sunday's game against the Jaguars, but the back-to-back absences from practice to begin the week don't bode well for his chances of gaining clearance to play.