Carlisle Conservatives have taken overall control of the city council after a Labour councillor joined the group.
Jo Ellis-Williams, who represents Parklands and Harraby South, said Labour no longer represented her values and claimed she had had enough of in-fighting within the group.
She said: “I got involved in politics to help people, to improve lives and improve the area we live. It has become increasingly apparent locally that the Labour Party is no longer the place to achieve that.
“I don’t feel my core values of increasing fairness and prosperity have changed; it just doesn’t seem to me that the Labour Party in Carlisle is capable of delivering on these values anymore. They are too busy squabbling amongst themselves.
“This in-fighting, point scoring and focusing on the nurturing of grievance has created an ugly culture of self-interest amongst some party members.”
Ms Ellis-Williams however did thank those members of the Labour Party who have been supportive, and helpful over the last few years, adding that she hoped they understood that that her move was not a rejection of that friendship.
John Mallinson, leader of the city council said: “The Conservative Group is absolutely delighted to welcome Jo to our group as well as the party.
“Jo is a well-known, well respected and a hardworking member of the council, who I am sure will be a great asset to us.
“Additionally, it now means that the Conservative group has overall control of the council, which along with a Conservative Government and a Conservative MP in Carlisle will assist us in delivering the Levelling up agenda by perusing the many government funded projects in the city at this time.”
Carlisle MP John Stevenson said: “I am delighted to welcome Jo to the Conservative Party. It is particularly good to see people with ambition join a party that has a real aspiration for the future of Carlisle and want to play their part in making it happen. I am sure Jo will make a valuable contribution to the party locally and to Carlisle City Council.”