Paul Davis, the House minority leader from Lawrence, filed papers Thursday to create a campaign committee to run for governor next year against Republican Sam Brownback.
Davis, 41, becomes the early favorite to win the Democratic nomination for what will be viewed as an uphill fight against the incumbent.
Davis appointed former Republican state Rep. Bill Kassebaum of Burdick to serve as his campaign treasurer. Kassebaum is the son of former Kansas Sen. Nancy Kassebaum Baker.
Davis said he will make a formal announcement of his plans in the coming weeks.
The announcement almost certainly means that Jill Docking of Wichita, a former chair of the Kansas Board of Regents, will not enter the Democratic primary at least as a gubernatorial candidate.
Docking had spend several weeks considering the race.