Berlin , Germany -LRB- CNN -RRB- -- German President Horst Koehler resigned suddenly Monday over what he said was heavy criticism about comments he made on Germany 's military role in the world , which he said had been misinterpreted . It was the first time in German history that a president has resigned , the government-funded Deutsche Welle news agency reported . Koehler said May 22 upon his return from a trip to Afghanistan that `` in emergencies , military intervention is necessary to uphold our interests , like for example free trade routes , for example to prevent regional instabilities which could have a negative impact on our chances in terms of trade , jobs and income . '' He later said he meant the protection of shipping routes along the Gulf of Aden against piracy , for example , and not any reference to Germany 's role in Afghanistan . But his comments came in for widespread criticism . Crticis said he was framing Germany 's involvement in the Afghan war in economic terms having to do with self-interest , rather than as a duty in fulfilling a NATO mission in the fight against terrorism . Others said his comments indicated he would use the military unconstitutionally and for economic reasons . Germany has 4,500 troops in a NATO-led force fighting a Taliban-led insurgency in Afghanistan . Polls show that most Germans oppose the war in Afghanistan , but the government has not set a date for the withdrawal of troops . Koehler , 67 , made the surprise resignation announcement at a televised news conference with his wife standing next to him . He appeared visibly emotional , the Deutsche Welle news outlet reported . `` I am resigning my post as federal president with immediate effect , '' Koehler said . `` It was an honor for me to serve Germany as president , '' he said . `` I thank the many people in Germany who have put their trust in me and supported my work . I ask for you to understand my decision . '' The president 's office is largely ceremonial . Chancellor Angela Merkel heads the government and holds the real power . Merkel found out about the resignation a short while before Koehler 's announcement , Deutsche Welle said . She canceled a trip to northern Italy to visit the training camp of the German national soccer team as the squad prepares for next month 's World Cup , the government news agency said . Speaking at a news conference in Berlin , Merkel said she was stunned by Koehler 's decision . ' I deeply regret this resignation , '' Merkel said . `` I must add that I of course told him also I respect his decision to resign . '' Merkel also said she had `` unsuccessfully tried to get him to change his mind , '' Deutsche Welle said . The resignation comes at an inopportune time for Merkel , whose center-right coalition recently lost an important state election and suffered another resignation of a key ally last week , Deutsche Welle said . The German constitution mandates that the head of the Bundesrat , the upper house of parliament that represents Germany 's federal states , will temporarily take over the president 's duties . Jens Boehrnsen , the Social Democratic mayor of Bremen , holds the rotating position of Bundesrat leader this year and will assume the president 's duties . Boehrnsen will fill in for Koehler until an electoral college , the Federal Convention , elects a successor . The convention must convene within 30 days -- by June 30 in this case . The president in Germany is not elected by the people , but by the Federal Convention . The secret ballot vote is held without prior debate and requires an absolute majority to elect a president . If none of the candidates wins an absolute majority after two rounds of voting , the person with a simple majority in the third round is selected president . The Federal Convention is Germany 's largest parliamentary body . All of the members of the lower house of parliament , the Bundestag , can vote . A corresponding number of representatives from the federal states also are entitled to vote . The convention , which had 1,224 members at the time , last met in May 2009 to re-elect Koehler . Koehler , a former managing director of the International Monetary Fund , was first elected president in 2004 .