International Monetary Fund managing director Mr Horst Koehler is set to become Germany's next president after the main opposition parties agreed to nominate him.
"I am assuming the next president will be called Dr Koehler," FDP parliamentary floor leader Mr Wolfgang Gerhardt told a news conference.
The support from the FDP followed a decision overnight by the main opposition conservative parties that Mr Koehler was their first choice for the largely ceremonial post.
The conservatives and FDP have a majority in the special assembly of Germany's lower and upper houses of parliament that will elect the country's head of state in May to succeed Mr Johannes Rau, who is retiring.