On 28 November, West German Chancellor Helmut Kohl outlined the 10-Point Plan for the peaceful unification of the two German states, based on free elections in East Germany and a unification of their two economies. In December, the East German "Volkskammer" eliminated the SED monopoly on power, and the entire Politbüro and Central Committee—including Krenz—resigned. The SED changed its name to the Party of Democratic Socialism (PDS) and the formation and growth of numerous political groups and parties marked the end of the communist system. Prime Minister Hans Modrow headed a caretaker government which shared power with the new, democratically oriented parties. On 7 December 1989, an agreement was reached to hold free elections in May 1990 and rewrite the East German constitution. On 28 January, all the parties agreed to advance the elections to 18 March, primarily because of an erosion of state authority and because the East German exodus was continuing apace; more than 117,000 left in January and February 1990.