“The deputy leader of Sheffield City Council has resigned after a petition was submitted calling for a referendum on the way the authority is run.
More than 26,000 people have backed calls for the authority to move from a strong leader model to a committee system of decision making.
By law a petition signed by 5% of voters – 20,092 – will trigger a vote.
Olivia Blake said she was stepping down from her role in order to back the petition.
A council spokesman said if the petition was deemed valid a city-wide vote would take place by May 2020.
Ms Blake said: “My preference was to resolve the debate on the council’s governance structure without the need for a referendum but now that it is almost certain to be held, it is time to take a public position on where we go next.
“I will take the side of the people. I will back the committee system. It is a starting point for a wider debate on how to rejuvenate our democracy, and it is important that Labour voices contribute to this debate.
“I have added my name to the It’s Our City petition, and will make further statements in the coming days about the role I intend to play in the upcoming referendum.”
Sheffield City Council has 84 elected councillors across 28 wards, but under the current model it is the council leader and nine cabinet members who make decisions on “the most significant issues”.
Co-chair of It’s Our City Ruth Hubbard said the existing system “places power in the hands of too few”.
“We want our city to work for all of us but at the moment it’s failing,” she said.
The council now has one month to verify the signatures on the petition.
James Henderson, director of Policy, performance and communications at Sheffield City Council, said: “If a valid petition is submitted by It’s Our City then we are required to hold a referendum on changing the council’s governance system.”