Rapoport listed the Minnesota Vikings, Arizona Cardinals and Tampa Bay Buccaneers as interested parties, but if the Chiefs can't swing a deal, the team will release Cassel, who started 47 games over the past four seasons in Kansas City.
None of this comes as a surprise. The writing was on the wall as soon as new Chiefs coach Andy Reid swapped two draft picks to the San Francisco 49ers for Alex Smith. On Tuesday, the Chiefs added Chase Daniel as Smith's backup, leaving Cassel floating in the wilderness.
Quarterbacks have nine lives in this league, and we wouldn't be surprised to see Cassel wind up back with Bill Belichick in New England if a trade partner can't be found. It's hard to imagine the Chiefs getting much value for such a shaky signal-caller.
Follow Marc Sessler on Twitter @MarcSesslerNFL.