Miller was first elected to the Minnesota House of Representatives in 2014. In December 2018, Miller, along with three other House members, formed a separate 'New House Republican Caucus' out of dissatisfaction with the Houseminority leadership. Miller wrote a letter to his GOPcolleagues stating that "the attitudes and actions by the HRC leader and some of his supporters have become too hostiletoward me" and pledged to continue opposing "radical liberalism".