The development, first reported by Seattle radio station KJR-AM 950, comes after the team allocated $8.3 million for linebacker Leroy Hill in naming him their franchise player. The team has $20.7 million in 2009 salary-cap space allotted for Peterson, Hill and fellow linebacker Lofa Tatupu.
Peterson's contract, a seven-year deal running through the 2012 season, calls for $6.5 million in salary for 2009. Counting bonus money already paid, the contract counts $8.8 million against the salary cap if Peterson remains on the roster and $4.6 million if the team releases him.
Peterson, 30, is a five-time Pro Bowl choice. He has earned Pro Bowl honors after each of his three seasons in Seattle, most recently as an injury replacement for Tampa Bay's Derrick Brooks.
Tatupu, 26, is a three-time Pro Bowl choice. Hill, also 26, has not appeared in a Pro Bowl, but Tatupu and Peterson have said he might be the best linebacker on the team.
Mike Sando covers the NFC West for ESPN.com.