Sharp is available on a Bosman transfer from cash-strapped Huddersfield Town, and the club are bringing him in as a replacement for Andy Dawson who has taken a better pay deal at Hull City.
28-year-old Sharp began his career at Auxerre, going on to play for Leeds, Wigan and Huddersfield.
He has held talks with Uniited chairman Steve Wharton and assistant manager Russ Wilcox and will sign subject to him passing the medical.