Mankins' agent, Frank Bauer, delivered some ominous words about the situation Friday night.
"They have totally lost this player mentally," Bauer told Boston Globe reporter Albert Breer. "For this young man to work like he has and play for the club for five years, and be promised he'd be taken care of, and to throw the offer they did across the table? It was never, ever a five-year deal. They wanted six years, they wanted seven. They have to do what they have to do, and we'll do what we have to do."
In an interview with ESPNBoston.com's Mike Reiss in June, Mankins said "I want to be traded. I don't need to be here any more."
Mankins is not holding out because he's not under contract. Quirky rules for the uncapped season switched him from unrestricted free agency to restricted, giving the Patriots serious leverage.
But Mankins might have gotten some when his replacement, Nick Kaczur, suffered a potentially serious back injury that could wipe out his season. The Patriots are down to third-stringer Dan Connolly at left guard.
The Patriots have until Sunday to present Mankins' camp with a letter of intent to place him on the roster exempt list, a mechanism that would allow the Patriots to sign somebody else for their 80-man roster. Players on the roster exempt list must sit out the first three games after signing a contract.
Bauer has told Boston reporters he hasn't spoken to the Patriots since May.
"They don't care," Bauer told Breer. "I would expect them to do everything nasty that they can."