Sanders, who turns 26 on Sunday, is a restricted free agent, and the Steelers tendered him at the original round level, meaning that if another team were to offer him a contract, Pittsburgh would have the right to match it or receive a third-round draft pick, where Sanders was drafted in 2010.
If Sanders stays in Pittsburgh his 2013 salary will be $1.33 million.
Listed at 5-11, 186 pounds, Sanders is a fast, versatile receiver, capable of playing multiple positions.
Playing in all 16 games last year (seven starts), the SMU product had 44 catches for 626 yards (14.2 yards per reception), though just one touchdown.
Pittsburgh is in a difficult cap situation, so depending on the contract the Patriots offered, it could be difficult for the Steelers to match.
The two sides could also work out a trade, as New England did with Miami in 2007 to get Wes Welker, who was also a restricted free agent at the time.