Sen. Claire McCaskill (D-Mo.) announced Monday that she won't run for governor in 2016, though she may face a potentially tough Senate re-election in 2018.
"I have an amazing job. I am challenged every day. I am so grateful to the people of Missouri for trusting me with this U.S. Senate seat, and I love the work," she said. "The work is too important, the job is too rewarding and too fulfilling and I just don't feel like I can turn away from it."
McCasill said she believes she can make the biggest impact in the Senate.
The announcement on a local Kansas City, Missouri, radio station ended months of speculation as to whether she'd mount a gubernatorial bid to succeed Democratic Gov. Jay Nixon. McCaskill had been cited as one of the red-state Democrats mulling a gubernatorial bid in order to have another political option, given the difficulty of running for Senate in a Republican-leaning state in a non-presidential year.
A gubernatorial bid in 2016 would have been McCaskill's second try for the office. When she was the state's auditor, McCaskill lost the 2004 race to then-Missouri Secretary of State Matt Blunt, a Republican. She had defeated then-Gov. Bob Holden in the Democratic primary that year.
McCaskill, who was first elected to the Senate in 2006, made history as the state's first elected female senator. She was elected to a second term in 2012 after capitalizing on comments by the GOP nominee, former Rep. Todd Akin (R-Mo.), about "legitimate rape" and pregnancy.
Missouri has never had a female governor. Attorney General Chris Koster, a former Republican state senator, is the highest-profile Democrat who has announced plans to seek his party's nomination.
McCaskill has distanced herself from the Senate's Democratic leadership to more closely align herself with the politics of her state and declined to support Sen. Harry Reid (D-Nev.) for the Senate's minority leader. On the radio show Monday, she said she wanted to continue working on "compromise legislation" as she completes her second term.
Last year, McCaskill had shot down speculation she'd seek the Democratic gubernatorial nomination.
"I am very happy in the job I have, and I am very lucky to have it,'' she said in a September interview with St. Louis Public Radio.
Hear the clip above.