Northumberland County Council's Conservative leader has been ousted in a vote of no confidence.
Councillor Peter Jackson's removal comes after chief executive Daljit Lally was put on "extended leave" in August when she raised concerns.
The Labour group accused the leadership of "silencing" her and some cabinet members resigned their posts.
During a meeting held via videolink a motion of no confidence in Mr Jackson was passed by 33 to 32 votes.
The row began when it emerged Ms Lally had sent emails to councillors claiming she had "serious whistleblowing concerns" about the way the authority was being run, accusing Mr Jackson of possible "bias".
No official reason was given for her being placed on extended leave, and the authority's deputy leader and two other cabinet members quit in protest.
Neither Ms Lally nor Mr Jackson have commented publicly about the allegations.
The Local Democracy Reporting Service said that the Labour group leader Susan Dungworth, presenting the no confidence motion, described it as a "very sad day" for the authority as few councils had moved a vote of no confidence in their leader whatever their political make-up.
She said: "Our reputation is in shreds and we are the laughing stock of the region.
"Peter Jackson's... desperate attempt to save his reputation is causing incalculable damage to the reputation of this great county council, the staff who work for it and the people we represent, and it's actually causing damage to our reputation for failing to deal with it."
In response, Mr Jackson said: "I absolutely refute the things that have just been said."
He described the allegations as "ridiculous smears" and "bunkum" and added that he was proud of what he and his cabinet had achieved over the past three years.
"We need to stick together as a county council, stop this petty bickering, and focus on the things that matter to the people up and down this county," he said.
The council has no overall political control but it is run by the Conservative group, which has the most number of councillors.
A new leader will be elected from that party.