Mike Johanns was born on June 18, 1950, in Osage, Iowa, and he grew up on his family's dairy farm. He graduated from St. Mary's University of Minnesota in Winona and received a law degree from Creighton University in Omaha. He practiced law in O'Neill and Lincoln, Nebraska. Johanns served on the Lancaster county board from 1983 to 1987 and on the Lincoln city council from 1989 until 1991. In 1991, he was elected mayor of Lincoln, and he was reelected in 1995. In 1998, Johanns ran for governor of Nebraska and won. During his tenure as governor, he promoted the use of ethanol as fuel, and he was an advocate for rural communities, farmers, and ranchers. He was reelected governor in 2002.

Johanns resigned as governor in 2005 to become secretary of the Department of Agriculture in the administration of George W. Bush. He was sworn in as the twenty-eighth secretary on January 21, 2005. During his tenure, Johanns supported free trade, worked to fight obesity, promoted the use of renewable fuels, and expanded the USDA's conservation commitment. He resigned as secretary of Agriculture in 2007 to run for the U.S. Senate from Nebraska.