Press Association Sport understands the two parties are close to thrashing out a deal which would see the 32-year-old end an 11-month stay in the MLS with Toronto FC and return to English football.
However, the transfer could yet depend on United States striker Jozy Altidore, whose future has been the subject of intense speculation in recent weeks.
The switch would have to be ratified by the MLS, which operates an allocation process, and meet with Altidore's approval.
Nevertheless, Sunderland are keeping their fingers crossed that agreement can be reached within the next 24 hours as they attempt to boost their attacking resources to avoid another relegation fight.
Gus Poyet's side has scored just 18 goals in 21 Barclays Premier League games to date this season with frontmen Steven Fletcher, Connor Wickham and Altidore having contributed only six of them and the American yet to register this season.
Defoe only joined Toronto during the summer but despite having scored 11 goals in 16 league appearances after signing a four-year deal, he has not settled and has been courted by a series of Premier League clubs after it became clear he was looking to return home.
The Londoner, who worked briefly with Poyet during his time at Tottenham, has scored 19 times in 55 appearances for England, and the Uruguayan will hope he can bring a significantly greater goal threat to a club currently lying just a point above the relegation zone.
It is understood the personal terms of the deal reflect that urgency, with Sunderland prepared to invest heavily in his services for the next few seasons.
That is something Altidore has singularly failed to do since arriving on Wearside from Dutch club AZ Alkmaar in a Â£6.5million in July 2013.
The 25-year-old, who also signed a four-year deal, has scored just three times for the club in 52 outings.
Source : PA