Gary Peters' exit creates a highly contested U.S. Senate battleground seat expected to be coveted by both major political parties.

Multiple Michigan Democrats had identified Gov. Gretchen Whitmer and Pete Buttigieg as top possible Democratic contenders for the Gary Peters seat.

Michigan Gov. Gretchen Whitmer joins "CBS Mornings" to talk about her bestselling memoir, "True Gretch," and the importance of bipartisanship.