Green party councillors have leapfrogged the Liberal Democrats to become the official opposition in Norwich city hall.
The Norwich Greens won three more seats to take their tally in Norwich to 13, just two behind Labour on 15.
It was a bad night for the Liberal Democrats, who lost five seats to slip back to third place. The Conservatives now have five councillors in Norwich, having gained two more tonight.
Prospective parliamentary candidate Adrian Ramsay is hoping the result will help his bid to challenge former home secretary Charles Clarke in Norwich South.
"Thousands of Norwich residents have endorsed our positive campaign based on more environmentally friendly and socially fair policies for the city council," he said, calling for improved energy efficiency, recycling and protection of the city's "natural and historic assets".
Mr Ramsay added: "The Green party is now clearly the main challenge to Labour in Norwich."