She was elected to the Norwegian Parliament from Nord-Trøndelag in 2005. She had previously served as a deputy representative during the term 2001–2005.[1]
Kristoffersen was a member of the executive committee of the municipal council of Verdal Municipality from 1991 to 1995, later serving as mayor from 1999 to 2005. From 1995 to 1999 she was a member of Nord-Trøndelag county council.[1]