Sunderland boss Jack Ross is keen to bring in a new left-back before the transfer window closes.
Sunderland have been linked with Greg Taylor and Morgan Fox as Jack Ross searches for a left-back in the late stages of the transfer window, but both those deals have proven problematic.
Sunderland are now set to target Swansea City defender John, as they seek to do business on deadline day.
Swansea are said to be prepared to let go of John, although it is not yet clear whether Sunderland will take the Welsh international on a permanent deal or on loan.
John’s arrival could be crucial for Sunderland, as they are currently short of options at left-back.
Denver Hume has started as Ross’s first choice on the left hand side of his defence, but he was not available at the weekend.
Sunderland were forced to play Conor McLaughlin out of position at left-back against Peterborough United, and that arguably did not help their cause at London Road.
Sunderland were beaten 3-0 by Posh, as they fell to their first defeat of the season, in what was a very disappointing result.
If John does sign he could make his debut for Sunderland after the international break against Accrington Stanley, although Ross has previously hinted that Hume still holds the shirt, after his start of the season.