It has been a foregone conclusion for months that Jeremy Lin will re-sign with the New York Knicks, but sources close to the situation say the return of the free agent point guard is not as certain as it once seemed.

While both Lin and the Knicks are hoping for a reunion, sources say that if any clubs offer Lin, a restricted free agent, a backloaded contract that pays him an eight-figure salary in the third and fourth years, the Knicks could be given pause about matching the offer.

With the new collective bargaining agreement employing a more punitive luxury tax, beginning in the 2013-14 season, the Knicks are extremely concerned about the financial ramifications of such a deal.

Toronto is perhaps the only team that might consider offering Lin a backloaded contract, known as a "poison pill" deal. The Raptors are currently going all-out to sign Steve Nash. Toronto has offered Nash a three-year deal worth $36 million, sources told ESPN.com's Marc Stein.

But if Nash, who is also considering Phoenix, New York, Dallas and Brooklyn, rejects Toronto's offer, the Raptors may turn their attention toward Lin.

The Knicks can offer Lin a four-year deal worth $24.5 million. But an opposing team can offer Lin a poison pill that could go as high as $40 million over four years. Such a contract would pay Lin $5 million in each of the first two years and then go as high as $15 million in each of the last two years.