Minchew became involved with the Loudoun County Republican Committee after his move to Leesburg, and was twice elected county Republican chair. In late 2005, Senator Bill Mims resigned his 33rd district Senate of Virginia seat to become Chief Deputy Attorney General. Minchew ran for the Republican nomination, finishing second in a four-way race, behind Loudoun County Supervisor Mick Staton. Staton lost the ensuing special election to DemocratMark Herring. The 10th House district was moved from the Martinsville area, on Virginia's southern border, to the northern tip of the state in the 2011 redistricting. Minchew won a three-way Republican primary in the new district, defeating his closest competitor, attorney John Whitbeck, by 87 votes. He defeated Democratic candidate David S. "Dave" Butler in the general election, 8140–5789. In 2013, Minchew faced no challenger for the Republican nomination. His general election campaign included a TV ad touting his accomplishments Minchew was endorsed by the National Federation of Independent Business, the Virginia Farm Bureau, the Virginia Association of Realtors, the Loudoun County Chamber of Commerce, and the Virginia Education Association, as well as the Loudoun, Frederick, and Clarke County Education associations, the Washington Post, and the Loudoun Times-Mirror. Minchew won re-election in the general election, decisively defeating Democratic challenger Monte A. Johnson, 12,950 - 9,723. In 2015, Minchew again faced no challenger for the Republican nomination. In the general election he faced Democrat Peter Rush, a Leesburg resident and formerly a member of the Loudoun County Soil and Water Board. Minchew won re-election 10,415-6,355. This was his largest margin of victory since taking office. In 2016, Minchew introduced HB 1181, which would have forced Virginia's representatives to the Electoral College to vote according to how individual congressional districts voted rather than how the state voted overall. The bill was criticized for being highly partisan, as the system of voting would give an advantage to Republican presidential candidates. Virginia's current winner-takes-all system is shared by 47 other states and the District of Columbia. In 2017, Minchew was defeated in his bid for a fourth term in the Virginia House of Delegates, losing to Democratic candidate Wendy Gooditis 15,151-14,014.