BERLIN (AP) -- Germany's labor minister is an early favorite for the presidential nomination, a day after President Horst Koehler's surprise resignation, according to an official quoted by a local news agency Tuesday.

Ursula von der Leyen would become the country's first female president if nominated by Chancellor Angela Merkel's coalition government and then approved by lawmakers.
Merkel launched a fast-track process to find a candidate. The new head of state has to be elected by June 30.
Following initial consultations between Merkel and her coalition partners, news agency DAPD reported that von der Leyen appeared to be the chancellor's favorite candidate to replace Koehler in the largely ceremonial post.
Von der Leyen, 52, is a member of Merkel's conservative Christian Democratic Union. The mother of seven has served in Merkel's Cabinet since 2005 and is considered a pragmatist.
A coalition official told DAPD that Merkel's party and its Bavarian-only sister party CSU support von der Leyen. The third coalition partner, the Free Democrats, has yet to decide, DAPD reported.
A government official told The Associated Press on condition of anonymity because of the sensitivity of the talks that no candidate “had yet been confirmed, but that the decision will be made in the coming days.”
Koehler stepped down Monday because of what he thought was unduly harsh criticism after an interview he gave on the German military's role in the world.
Koehler said in his very brief resignation statement he felt the criticism after his interview showed too little respect for his office. That criticism was first voiced by the opposition. Merkel had declined to comment on it.
Merkel said Monday night that Koehler had given her only two hours warning. She tried to make him change his mind, but failed, she said.
“My heart was very heavy today because I know a lot of citizens appreciate him,” Merkel said.
While speculation about possible replacements had started immediately and von der Leyen was one of the first to be named along with the speaker of the parliament, Norbert Lammert, among others, Merkel said at that point that the race was “completely open.”
She vowed to propose a candidate who “has a chance to be accepted by all.”
The president will be chosen by an assembly of 1,244 representatives from the state and federal parliaments, where Merkel's coalition has a majority.