Born in Fairmont in 1967, Tennant became the first female Mountaineer mascot at West Virginia University in 1990. After working in TV news, she ran for secretary of state in 2004 but lost in the Democratic primary. In 2008, she won the office and focused on expanding online voting for military and overseas residents.

Following Senator Robert C. Byrd's death in 2010, Tennant was involved in debates about special elections. She ran for governor in 2011 but lost the primary to Earl Ray Tomblin. Reelected as secretary of state in 2012, Tennant later ran for U.S. Senate in 2014 but lost to Shelley Moore Capito. In 2016, she lost the secretary of state race and in 2024, won a seat on the Kanawha County Commission by fewer than 400 votes.