Bush wasn't able to practice Wednesday, and a team source said no final determination has been made on the running back's status for Sunday night's showdown with the Pittsburgh Steelers. However, it doesn't look promising.
"We just keep taking it day to day and monitoring the progress, monitoring the next day after the workout and kind of go from there," Payton said.
The Saints (4-3) say they don't like to use injuries as an excuse for sagging performance, but there's no question that a number of key players have missed action while New Orleans has lost three of its last five games.
"The disappointing part is you haven't seen the complete team since Week 2 when Reggie went down," Shanle said. "It absolutely has an effect. I mean, we do a good job of having guys who are backups come in and play good football, but there's a reason why Reggie Bush is Reggie Bush and Pierre Thomas has done what he's done."
In the same game that Bush went down, nickel back Randall Gay was concussed and, following a brief comeback, went on season-ending injured reserve.
Thomas, last year's leading rusher and a productive outlet for quarterback Drew Brees on screen passes, sprained his ankle in Week 3.
Harper missed a Week 4 contest against the Carolina Panthers with a hamstring pull. Porter, who also went down in Week 4, needed arthroscopic surgery to repair the lateral meniscus in his left knee and hasn't played since. Smith strained his groin in Week 4 and missed the next game.
Shanle pulled a hamstring in practice in Week 6 and has missed the past two games. Greer left the Week 6 game at Tampa Bay with a left shoulder injury and has yet to return.
All-Pro safety Darren Sharper, who opened the season on the physically unable to perform list while recovering from offseason knee surgery, finally came back last weekend to a defensive backfield that played without its top three cornerbacks.
Thomas, who has been absent during recent practices, was on the field in a jersey, participating in the team stretch and doing some light jogging.
Shanle returned to practice on a limited basis. While Porter and Greer weren't officially listed on the Saints' injury report as having practiced, both attended and did some light individual work.
"The progress with both Jabari and Tracy has been significant and positive and on schedule," Payton said.
Bush, Thomas and Porter weren't available to speak with reporters after practice. Greer said he was "optimistic" about returning this Sunday, as was Shanle.
Brees said the Saints believe their best football is still to come, adding that the rash of early season injuries could pay off in the long run.
"We faced this last year, but just later on in the season," Brees said, referring to the Super Bowl champs' three-game skid just before the playoffs. "Obviously we're facing it much earlier now.
"Are we more injured than other teams? Probably most of them," Brees continued. "It's allowed an opportunity for some young guys to step up and play pretty well. I think that will serve us well down the road, once we get everybody back."
The Associated Press contributed to this report.