David Whitley, who served as the Texas secretary of state for about five months and was the face of a failed attempt to review the citizenship status of nearly 100,000 registered voters, resigned from his post Monday.

Mr. Whitley was appointed by Texas Gov. Greg Abbott, a Republican, in December, but he was never officially confirmed as the secretary of state by the Texas Senate because all 12 Democrats refused to approve him.

Absent that confirmation, according to state regulations, the end of the legislative session Monday would have marked the end of his tenure.

Mr. Whitley stirred up controversy in January when his office warned county officials that the Texas Department of Public Safety had identified about 95,000 registered voters as potential noncitizens, adding that 58,000 of those had voted in one or more elections in the state.