He was the candidate of the two Christian Democratic sister parties , the CDU and the CSU , and the liberal FDP , for becoming President . KÃ hler was elected to his first five-year term by the Federal Assembly on 23 May 2004 . As the candidate of the two Christian Democratic sister parties , the CDU and the CSU , and the liberal FDP , KÃ hler was elected to his first five-year term by the Federal Assembly on 23 May 2004 and was subsequently inaugurated on 1 July 2004 .