Micky Adams has quit as Leicester boss after two-and-a-half years in charge.
The Foxes board "reluctantly accepted" the 42-year-old's resignation after an attempt to change his mind failed.
Adams said: "There has been criticism of me from supporters and I can understand and respect that. Perhaps I have taken this club as far as I can.
"It is time for the mantle to pass on. I've not enjoyed the past few weeks. This is not a knee-jerk reaction, I've been thinking about it for a while."
Chief executive Tim Davies said: "Everyone is deeply saddened that Micky has decided to tender his resignation. And we have accepted it with a heavy heart.
"Everyone connected with the club wanted Micky to stay and we did our utmost to try to persuade him."
Adams' assistant Alan Cork has also left and director of football Dave Bassett has been placed in temporary charge of team affairs.
Former Leicester striker Mike Newell has already been linked with the job after steering Luton to the top
of League One.
Others who could be in the frame include fellow Foxes favourite Gary McAllister and Burnley boss Steve Cotterill, who had a spell at the Walkers Stadium as coach last season.
But Davies added: "We are very lucky to already have Dave Bassett at the club.
"He is a very experienced manager and we are in no rush to bring anyone in."
Leicester were favourites to bounce straight back from last season's relegation from the Premiership, but are only 12th after picking up just one home win.
There have been reports of dressing room unrest and summer signing Martin Keown was recently put on the transfer list after apparently criticising Adams' manager methods.
Last season Adams offered to resign after nine Leicester players were arrested on sexual assault charges while on a winter break in La Manga, but the board gave him their full backing.
He added: "Three years is a long time in football and to say my time here
has been eventful would be something of an understatement."
Adams joined the club as assistant to Bassett in October 2001, following Peter Taylor's departure, but the duo could not prevent the team from being relegated.
He took charge six months later and, despite seeing the club slide into administration, inspired the Foxes to bounce back at the first attempt.
Davies added: "He has been manager during arguably the most difficult period in the club's modern history.
"His achievement in steering the club to promotion in the season in which the club went into administration is a truly remarkable feat."
Despite his turbulent time at the Walkers Stadium, Adams is determined to return to the game in the near future.
"I feel I still have a lot to offer the game. It's often said in these circumstances that a manager likes to take a break and take stock of his options," he said.
"I will sit down with my family and think things through but I hope to continue as a manager. It's what I have done for several years now and I love the job."