On July 14, 2020, Sheffield was defeated in his re-election effort by Stephenville, Texas attorney Shelby Slawson by over 20% in the Republican primary runoff.
In the Republican primary in 2010, Sheffield polled 44.2 percent in his challenge to incumbent Sid Miller who had held the office since 2001.
[6] Sheffield easily won in the November general election with 78% of the vote district wide against Bill Norris, the Democratic nominee and a retired school teacher from Dublin.
[11][12] On July 14, 2020, Sheffield was defeated in his re-election effort by Stephenville, Texas attorney Shelby Slawson by over 20% in the Republican primary runoff.
[11] During his time in the Legislature, Sheffield served on the Texas House committees of Appropriations, Corrections, Public Health, Rules and Resolutions.