Former U.S. Attorney Catherine Hanaway says she is running for Missouri governor in 2016.
Hanaway's announcement Monday makes her the first Republican to enter the race. Democratic Attorney General Chris Koster has been building a gubernatorial campaign since last year.
The office will be open because Democratic Gov. Jay Nixon is barred by term limits from seeking re-election.
Hanaway is a former state lawmaker from St. Louis County who in 2003 became the first women to serve as Missouri House speaker after helping Republicans win a majority in the chamber.
She lost a bid for secretary of state in 2004 but was appointed the next year by President George W. Bush to serve as U.S. attorney for the eastern Missouri. She held that position until April 2009.