Campagna and Leivo each chipped in with two assists for the Wolves (15-16-7) while Nicholas Baptiste and Nathan Pancel had a goal and an assist apiece.
Campagna is currently the hottest player in the OHL as he's picked up a point in 13 straight games and has five goals and 19 assists in the process.
Leivo, a prospect of the Toronto Maple Leafs, pushed his point streak to eight games and has three goals and 11 assists during his streak.
Charlie Dodero and Jacob Harris also scored for Sudbury and Joel Vienneau stopped 26 shots for his 12th victory of the season.
Ryan Sproul scored the lone goal for the Greyhounds (18-17-2), who had their winning streak halted at four games, and Matt Murray turned aside 36 shots.
Sudbury, who has the OHL's third-best power play on home ice, finished the game 3 for 7 with the man advantage while Sault Ste. Marie went 0 for 3.
Elsewhere in the OHL, it was: Mississauga 5, Brampton 4 (SO) and Owen Sound 4, Oshawa 2.
At Sudbury, Ont., Baptiste opened the scoring for the Wolves on the power play at 14:42 of the first period, but Sproul replied with a shot from the slot a minute later to tie the game.
Dodero made it 2-1 on the power play when he unloaded a blast from the point that beat Murray blocker side at 7:05 of the second period and Harris increased the lead after he banged in a loose puck in the crease at 11:00.
Pancel added a power-play goal at 18:30 of the third period after he backhanded the puck over a sprawling Murray.
Steelheads 5 Battalion 4 (SO)
At Mississauga, Ont., Dylan DeMelo scored twice, including the tying goal at 19:11 of the third period to force extra time, and Kristoff Kontos scored the winner in the seventh round of the shootout as the Steelheads (19-13-3) came from behind to beat Brampton (18-14-7), which lost for the first time in three outings.
Attack 4 Generals 2
At Oshawa, Ont., Keevin Cutting, Gemel Smith and Nathan Chiarlitti scored third-period goals as Owen Sound (25-8-3) came from behind to double up the Generals (21-13-3), who had their four-game win streak snapped.