Cammalleri, 31, and Stempniak, 31, are both pending unrestricted free agents, set to hit the open market July 1.
According to a league source, contract talks between Cammalleri and the Flames have not gone overly well, despite the team recently presenting him with a multi-year offer.
Flames president of hockey operations Brian Burke confirmed the offer to The Fan 960 in Calgary, but also told the radio station that he "would not predict" whether they'd come to terms on a deal.
"We've offered him an extension," said Burke, who met with Cammalleri and his agent Ian Pulver. "We have not gotten a deal done. We will continue to talk and a trade is a possibility, no question about that, but re-signing him is a possibility too. We'll see."
Negotiations between the Flames and Stempniak have not been fruitful, either, and it's unclear if talks will continue.
Cammalleri also owns a limited no-trade clause and can list up to seven teams he won't accept a move to. That list was originally submitted in the off-season, when the Flames explored trading him, and it's unclear if it's been recently revised.
The Vancouver Canucks, New Jersey Devils, Ottawa Senators and Phoenix Coyotes are believed to be interested in Cammalleri.
Stempniak has caught the eyes of Tampa Bay Lightning and Columbus Blue Jackets, among other clubs.