Tigers boss Peter Taylor had doubts that a transfer would go ahead due to a niggling calf injury, but Jefferies claims he's still tracking the defender.
He said: "We wanted to have a look at him a fortnight ago but unfortunately, John picked up an injury.
"He's one of a few who we'd like to keep an eye on so we've got between now and the end of the season to see what happens."
The 31-year-old's contract is up in the summer and Taylor has previously revealed that the Scotsman's future does not lie at the KC Stadium.
He won't be able to prove his fitness in this evening's scheduled reserve game with Sheffield Wednesday as the Church Road pitch is again waterlogged. The fixture hasn't been re-arranged yet, nor have the previously postponed games with Bradford and Huddersfield. Unless any of them can be fitted in next week, City reserves' next match will be at Walsall a week on Monday.