North End took a deserved lead when Andy Carroll headed in Kevin Nicholls's inswinging free-kick after 14 minutes.
But Leicester improved after the interval and drew level after some great play by Matt Fryatt.
Fryatt weaved his way past a couple of challenges on the edge of the box and his cross was nodded in by fellow striker Campbell.
Leicester caretaker manager Frank Burrows:
"The supporters are used to better and want to get back to the Premier League and we are all aware of that," he said.
"The management situation's down to the chairman. Whoever gets the job will be expected to move onwards and upwards. "I'm enjoying it and I still get a buzz out of it. There things not to like about it but it's a disease and I am afflicted with it."
Preston: Lonergan, Jones (Davidson 46), Mawene, St. Ledger, Hill, Sedgwick, Nicholls, McKenna, Whaley, Carroll, Ormerod (Agyemang 73).
Subs Not Used: Chris Neal, Hawley, Mellor.
Goals: Carroll 14.
Leicester: Fulop, N'Gotty, Kisnorbo, McAuley (King 36), Stearman, Chambers, Kenton, Sheehan, Fryatt, John (Cort 58), Campbell (Newton 79).
Subs Not Used: Henderson, Maybury.
Goals: Campbell 59.
Ref: Colin Webster (Tyne & Wear).