He was the last Democrat to hold statewide office in South Carolina, until the appointment of Brian J. Gaines as Comptroller General by Governor Henry McMaster in 2023.

[3] McGill became lieutenant governor after Glenn F. McConnell resigned to become president of The College of Charleston, becoming the first Democrat to hold the office since 1995.

In January 2015, McMaster appointed McGill to be the State Director of South Carolina's Office on Aging.

[3][6] In March 2016, McGill left the Democratic Party and announced his intention to run for governor of South Carolina as a Republican in the 2018 election.

[3] McGill was considered a long-shot contender in the Republican gubernatorial race, raising less money than McMaster or Catherine Templeton.