Sullivan has given the former Bolton, Blackburn and Newcastle chief a ringing endorsement.
He told The Sun: "Whether it's a popular decision or not, come what may we will stick with Sam.
"We have a reputation for honouring contracts and I genuinely believe there is no point chopping and changing every year if you want to build something. I believe in continuity.
"I keep hearing all this nonsense about our style of play and complaints from some fans, but Sam has an undeserved reputation which is hard to get rid of.
"I haven't missed a game all season and most of the time we have tried to play decent football.
"Sam has a two-year contract and if we don't get promoted in that time I doubt I would need to fire him. He's said himself that he would walk away."