Press Association Sport understands the former Wimbledon striker has held discussions over a role working alongside new director of football Joe Kinnear.
The 54-year-old played under Kinnear during their time together at the Dons and remains a close ally of the Irishman.
Sunderland-born Harford had a brief spell with the Magpies as a player from August 1981 to March 1982 having launched his career at Lincoln, and went on to play for Bristol City, Birmingham, Luton, Derby, Chelsea, the Black Cats, Coventry and Wimbledon, forging a reputation as a no-nonsense frontman.
He began his coaching career at Wimbledon before following Kinnear to Luton and then Nottingham Forest, and later became a manager in his own right at Rotherham, Luton and QPR.
Harford's 13 months as assistant to Karl Robinson at MK Dons came to an end in June, and it was later announced he was to take up a coaching role at Millwall.
Should he be appointed to assist Kinnear, the move would do little to ease the tension at St James' which was created when Kinnear was parachuted in above manager Alan Pardew by owner Mike Ashley.
The 66-year-old Irishman's arrival was greeted with both anger and astonishment as he was put in charge of all football-related matters, but particularly the club's transfer affairs.
To date, not a single senior player has been added to the squad, while Steve Harper, Danny Simpson and James Perch have been allowed to leave, although Harper and Simpson were always moving on anyway.
Pardew's priority is to recruit two proven strikers with Aston Villa's Darren Bent high on his list, although the ongoing stalemate over Papiss Cisse's refusal to wear the logo of sponsor Wonga on his shirt remains a serious complication.
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- Joe Kinnear