Both Newcastle and Sunderland remain hopeful about their chances of recruiting him.
Colback was officially permitted to talk to clubs on Monday about fixing up a new deal, and the Cats’ midfielder was due to make a decision last night on whether to sever his ties with Sunderland.
The Black Cats made a fresh contract offer last week after a fresh round of talks with sporting director Lee Congerton, but Newcastle are ready to pounce with a four-year contract offer if he decides to leave.
Whatever happens, it is likely to be concluded quickly.
The player wants his future resolved before he jets out on holiday and will be aware of interest from several Premier League clubs – along with Scottish champions Celtic, who have made an enquiry in the last fortnight.
But moving to the Scottish League would be a major mistake, and he knows that.
Colback has also attracted interest from West Ham, Aston Villa and Everton so the Magpies won't have it all their own way.
Everton could tempt him with European football, which has long been his ambition.