On November 4, 2014, McCaslin won the election and became a Republican member of Washington House of Representatives for District 4, Position1. McCaslin defeated Diana Wilhite with 58.0% of the votes.[4][5]
In multiple legislative sessions, McCaslin has proposed bills calling for the creation of a new state called "Liberty" carved out of Eastern Washington.[6]
In August 2021, McCaslin and four other state Republican lawmakers held an unofficial hearing with the aim of possibly calling for a "forensic audit" to take place in Washington State similar to the controversial Arizona audit. The group that organized the event also invited figures that have falsely claimed there was voter fraud in the 2020 presidential election.[7]