Olathe Johnson County District Attorney Phill Kline is running for re-election to the post.
The former attorney general made the announcement Monday night at a private gathering of supporters.
As attorney general and later as district attorney, the anti-abortion Republican has been embroiled in a battle against Planned Parenthood for alleged late-term abortions.
Kline took over the district attorney's office in January 2007. The Johnson County Republican Party's precinct leaders elected him to complete the term of Paul Morrison, who defeated Kline in the race for Kansas attorney general.
Morrison later resigned because of a sex scandal.