Despite the electoral victory of 53% won by Georgios Papandreou in the elections of 1964, the Centre Union was not able to govern the country for more than one and a half year. The provocative dismissal of the elected prime minister in July 1965 by the young king Constantine marked a series of open and calculated interventions of the Monarchy in the country’s political life.

The overthrow of the Centre Union government was brought about - among others - by eminent members of that same party, who formed a series of unstable, practically stillborn governments during the period July 1965 - April 1967. The leading members of ERE and the Centre Union (Papandreou-Kanellopoulos) had attempted to reach an agreement, in order to surmount the political stalemate and prolonged crisis through elections that would be conducted by a caretaker government. However, this attempt would be abruptly and violently interrupted by the military coup launched on April 21, 1967.