The elections were quickly denounced by both main opposition parties, the leftistUnited Democratic Left (campaigning as part of theAll-Democratic Agricultural Front) and theCentre Union. They refused to recognise the result because of the numerous cases ofvoter intimidation and irregularities, such as sudden massive increases in support for ERE against historical patterns and the voting by deceased persons. The Centre Union alleged that the election result had been staged by the agents of the shadowydeep state (παρακράτος), including the army leadership, theGreek Central Intelligence Service and the notoriously right-wingNational Guard Defence Battalions, according to a prepared emergency plan codenamedPericles (Σχέδιο «Περικλής»). Although irregularities certainly occurred, the existence ofPericles was never proven, and it is uncertain that the interference in the elections had radically influenced the outcome. Nevertheless, Centre Union leaderGeorge Papandreou initiated an "unrelenting struggle" ("ανένδοτος αγών") until new and fair elections were held.[2] Thus, the 1961 elections became known in the Greek political history as the "elections of violence and fraud" (εκλογές της βίας και νοθείας).