The Reds went ahead after just two minutes in this rearranged fixture when winger Nicky Ajose got on the scoresheet yet again.
Fellow midfielder Paul Pogba made it 2-0 to Paul McGuinness' side after 19 minutes, and the win was rounded off two minutes from time by Reds striker John Cofie.
United are now six points in front of second-placed West Bromwich Albion, while third-placed Everton are seven points adrift, but the have two games in hand.
The Reds have four games left this season and will be hoping to follow in the footsteps of United's Reserves, who clinched the Premier Reserve League North title.
United: Johnstone, Brown, Fornasier, Thorpe, McGinty; Cole, Pogba (Tunnicliffe 60), Morrison, Ajose (Hussain 78); Keane (King), Cofie.
Subs not used: Devlin, Lingard.