Councillor Lee Hunt blamed internal Tory "wrangling" for his decision
The Liberal Democrats have taken control of Portsmouth City Council after three councillors, including one Conservative, defected to their ranks.
Tory councillor Lee Hunt switched allegiance blaming internal "party wrangling" for his decision.
He was joined by independents Jason Fazackarley, a former Labour lord mayor of the city, and Leo Madden, a former Labour leader of the council.
It is the first time since 2000 that one party has gained overall control.
"It has been coming for about a year-and-a-half," said Mr Hunt who claimed to have received phone calls of support.
"The Conservative party for south Portsmouth has lost touch with the electorate.
"There's a small clique of people in the Conservatives that no one really wants - a band of about 12 people.
"They [the electorate] did not vote for me on a Tory mandate, they voted for me because I get things done. I put people first."
Mr Hunt, a former chairman of the Portsmouth South Conservative Association, is unhappy that the association has had a political falling-out the local party.
Also, he cited the appointment of former Winchester city councillor Flick Drummond as the Conservative prospective Parliamentary candidate for Portsmouth South as a sticking point.
He added: "The Lib Dems have been getting on with running the city while the Tories have been arguing among themselves."
The decision means the Lib Dems now have 22 councillors to the Tories' 18 and two for Labour.
Conservative councillor Alistair Thompson said there had "clearly been a falling out within Portsmouth South" and it was "sad" that it could not be resolved.
"It's very disappointing when people who have stood for one political party defect to another.
"I do wish him well, he's served the party for more than 10 years.
"I think he's wrong saying that the party has lost touch with the electorate, we clearly won the popular vote at the last local election.
"But in effect they've been operating a Liberal/Labour/Independent coalition - this is more about keeping the Conservatives out.
"We will keep putting forward exciting plans for the city, which the electorate have backed."
Mr Madden, the council's joint deputy leader member for health and social care, said: "I and Jason [Fazackarley], have decided to join the Lib Dems because they are a party that puts the interests of the people of Portsmouth first... rather than engaging in political posturing."