The Nebraska Republican announced in a statement Monday that he would not seek a second term. The former Nebraska governor and U.S. agriculture secretary says he and his wife, Stephanie, have decided that the time has come "to close this chapter of our lives."

Johanns joined the U.S. Senate in 2009. He served as agriculture secretary under President George W. Bush and was Nebraska's governor from 1999 to 2005.

The next question seemed to be, who would replace him? After Monday afternoon's announcement, the first person many were looking to was Governor Dave Heineman.

"I love being the Governor of Nebraska. Now I know my time is up here in a couple of years and I support that. I support term limits. That's appropriate. And until this morning, the farthest thing from my mind was the United States Senate," Heineman told reporters.

The two have known each other since Johanns was the mayor of Lincoln and Heinenman sat on Freemont City Council.

Joe Jordan of nebraskawatchdog.org says other possible names to look out for include mayor Chris Beutler from Lincoln, Chuck Hassebrook, and State Senator Steve Lathrop. Republican Congressman Jeff Fortenberry has also already expressed interest.