Wallace was elected as MP for the Lancaster and Wyre constituency in the 2005 general election. He won 22,266 votes with a majority of 4,171 (8.0%). The seat had previously been held by the Labour Party's Hilton Dawson. The constituency was abolished in 2010 and in the 2010 general election he was elected as MP in the new seat of Wyre and Preston North with 26,877 votes and a majority of 15,844 (30.9%). Wallace was re-elected at the 2015, 2017 and 2019 general elections.