As internal dissatisfaction grew in the early 1970s, and especially after an abortive coup by the Navy in early 1973, Papadopoulos attempted to legitimize the regime by beginning a gradual "democratization" (see also the article on Metapolitefsi). On 1 June 1973, he abolished the monarchy and declared Greece a republic with himself as president. He was confirmed in office via a controversial referendum. He furthermore sought the support of the old political establishment, but secured only the cooperation of Spiros Markezinis, who became Prime Minister. Concurrently, many restrictions were lifted and the army's role significantly reduced. An interim constitution created a presidential republic, which vested sweeping—almost dictatorial—powers in the hands of the president. The decision to return to (at least nominal) civilian rule and the restriction of the army's role was resented by many of the regime's supporters, whose dissatisfaction with Papadopoulos would become evident a few months later.
On 1 July 1973, The Observer published an article by Charles Foley claiming that the Central Intelligence Agency had engineered the coup and that unnamed senior officials in the Joint United States Military Aid Assistance Group in Athens regarded Papadopoulos as "the first CIA agent to become Premier of a European country". The source for much of Foley's story was Andreas Papandreou, the Minister of State in Charge of Intelligence in the government overthrown by Papadopoulos. The following day during William Colby's confirmation hearings to be Director of Central Intelligence, Colby was asked by Stuart Symington, chairman of the United States Senate Committee on Armed Services, if there was any justification for the assertions. Colby replied that he had the allegations researched and found that the CIA had not engineered the coup, Papadopoulos was not an agent of the CIA, and that Papadopoulos was never paid by the CIA. Colby added "[Papadopoulos] has been an official of the Greek Government at various times, and in those periods from time to time we worked with him in his official capacity." A clarifying statement was added to the record: "The only association the Agency ever had with Papadopoulos of any kind was in his capacity as an officer of the Greek Intelligence Service, with which we have maintained a liaison relationship since the Greek civil war in the late 1940s."
After the events of the student uprising of 17 November at the National Technical University of Athens (see Athens Polytechnic uprising), the dictatorship was overthrown on 25 November 1973 by hardline elements in the Army. The outcry over Papadopoulos's extensive reliance on the army to quell the student uprising gave Brigadier Dimitrios Ioannidis a pretext to oust him and replace him as the new strongman of the regime. Papadopoulos was put under house arrest at his villa, while Greece returned to an "orthodox" military dictatorship.