Portolesi decided to enter politics prior to the 2006 state election, and was nominated, unopposed, for preselection to the then highly marginal Liberal seat of Hartley. The traditionally Labor seat had been won by Joe Scalzi at the Liberal landslide of 1993, and as a popular local member, Scalzi went against the predictions to retain the seat in 1997 and 2002. Portolesi's status as an Italian-Australian broadened her support in the ethnically diverse community, and helped neutralise a factor that Scalzi had used to his advantage in the past.