Neumann was elected as an alderman for Brantford's fifth ward in 1976 and was re-elected without opposition in 1978. He became the city's mayor in 1980, defeating right-wing candidate Andy Woodburn and incumbent Charles Bowen, and was re-elected without serious opposition in 1982 and 1985. As mayor, Neumann helped expand Mohawk College, negotiated an agreement with Brant County that allowed Brantford to annex five thousands acres of land, concluded an agreement with the Six Nations to construct the Brantford Southern Access Road, and lobbied for the construction of Highway 403 to Ancaster.