April 19 the deadline on Sanders – New England Patriots Blog – ESPN Boston

Smart play for the Patriots is to wait here. Unless some other team swoops in on Sanders, they really have no reason to do anything just yet. 

Pittsburgh has holes to fill this offseason, and the Patriots (if they are still interested in Sanders) could be waiting for the Steelers to make other roster moves, which would further limit their cap space and ability to match an offer.