McCaffrey was a limited participant in Wednesday's practice, with the hamstring injury suffered on Sept. 23 in Houston.
He also did some limited work last week before sitting a second straight game. Rookie Chuba Hubbard started in his absence, and ran for 101 yards last week against the Eagles.
"It'll probably go to Sunday," Rhule said of McCaffrey. "It'll be a game-time decision. He's still limited. It could go one way or another right now."
Monday, Rhule said he was "hopeful" his starter might be able to go this week, but he wasn't ready to go that far Wednesday.
"Honestly, probably 50-50 on Christian," he said. "It's going to come down to how he feels. So we'll wait to see how he responds to today and go from there."
— The Panthers got a couple of offensive line starters back on the practice field Wednesday.
Left tackle Cameron Erving was back after missing last week with a neck injury. Left guard Pat Elflein was designated for return from IR after missing three weeks with a hamstring injury and practiced.
While they haven't activated Elflein yet (they have 21 days to do so), Rhule said the hope was that they could by the end of the week. Dennis Daley has started in Elflein's absence.
Last week against the Eagles, they shifted right tackle Taylor Moton to the left to fill in for Erving, but Rhule said the plan was to put him back on the right side this week to "keep a strength strong."
Moton is more comfortable on the right based on experience alone, as he hadn't started on the left since Week 2 of the 2018 season.
— Rhule also said that linebacker Shaq Thompson would not play this week, as he's recovering from a foot injury suffered in Dallas. They didn't put him on IR, so they apparently didn't consider it a long-term injury.
— The Panthers had to adjust the practice squad Wednesday, when Washington signed cornerback Corn Elder to its active roster.
To fill his spot, they signed veteran safety Doug Middleton to the practice squad. Middleton, an Appalachian State product who has played for the Jets, Dolphins, Jaguars, and Titans, was with the Panthers in training camp this summer.
The Panthers have brought safety Kenny Robinson up from the practice squad the last two weeks, but that's his limit for weekly promotions without signing him to the 53-man roster.
View photos from Wednesday's practice as the Panthers prepare to face the Vikings on Sunday in Week 6.