A team spokesman said Saturday that both players had been downgraded on the official injury report from questionable to out with knee injuries.
Both players are expected to be back at practice next week.
Bush missed practice this week with swelling in his left knee, the same knee on which he had surgery last December to repair cartilage.
Bush was coming off one of his best games of the season in St. Louis last Sunday, when he gained 98 yards and scored two touchdowns on six rushes and a pair of receptions.
Bush has 484 yards and six touchdowns in combined rushing and receiving this season.
Coach Sean Payton said this week he was hopeful Bush could play against the Buccaneers, but that he was wary of pushing him and causing a setback.
Ellis sprained his right knee in Miami in Week 7 and returned to practice this week on a limited basis. A first-round draft choice in 2008, he is one of New Orleans' primary run-stuffers.
The Saints' defense has yielded 151 yards rushing to Atlanta's Michael Turner, 149 yards to Carolina's DeAngelo Williams and 131 yards to St. Louis' Steven Jackson in the three full games Ellis has missed so far.