The Liberal Democrats have steadily gained ground and now need to win only eight seats to take control.
For the first time in many years officials from the national Labour headquarters have been called in to help the local group fight the elections.
The Lib Dems call it a 'smear one, smear all' approach, and said the Labour group was also spending huge sums on a full-colour campaign newspaper, glossy leaflets and a new campaign headquarters in the middle of the city.
Council leader Jan Wilson rubbished the smear claims, but said the party locally and nationally would be using all its resources to retain Sheffield. The council is split 50 Labour, 36 Lib Dem and one Conservative.