EPEK was established on 14 January 1950 as an electoral alliance between ex-Prime Minister Emmanouil Tsouderos' Democratic Progressive Party (Dimokratikon Proodeftikon Komma) and General Nikolaos Plastiras' Progressive Liberal Party (Komma Proodeftikon Fileleftheron).

[1] King Paul was initially suspicious of Plastiras and his speeches indicated that he was prepared to give amnesty to the defeated Communists.

Plastiras helped establish the Second Hellenic Republic in 1924 and twice - in 1933 and 1935 - tried to overthrow governments alleged to be plotting the restoration of the monarchy, though he now claimed to be fully reconciled with the dynasty.

[1] King Paul was initially suspicious of Plastiras and his speeches indicated that he was prepared to give amnesty to the defeated Communists.

Plastiras helped establish the Second Hellenic Republic in 1924 and twice - in 1933 and 1935 - tried to overthrow governments alleged to be plotting the restoration of the monarchy, though he now claimed to be fully reconciled with the dynasty.

The EPEK vote was particularly strong in impoverished refugee regions where Plastiras had a sizeable personal following who were mostly left-leaning anyway.

[4] Most importantly, the letter contained principles that all parties must follow, namely that all constituent parts must recognise Greece as a constitutional monarchy and that the Greek government must give its full support to the United Nations.

[7][8] King Paul met with the leaders of the three largest parties - Papagos, Plastiras and Venizelos - to discuss the formation of a government.

EPEK initiated a revision of the constitution, specifically granting women the vote, empowered the government to expropriate large estates for re-distribution to landless farmers and made provision for the Queen to act as regent in the King's absence.

[10] On 10 August, Plastiras unexpectedly returned from France, claiming that his health was fully restored and that he could resume his duties.

Although EPEK continued to exist until it was absorbed into the Centre Union in 1961,[16] it was no longer a forceful political element after General Plastiras died and never exceeded 15 seats in a national election under the leadership of Savas Papapolitis.