The DP started to lose the support of the people as of 1954. The main reasons for this were the end of favorable cycles in the foreign markets and a slow down in economic growth. In particular, rapidly increasing inflation upset the financial situation of the fixed income population in urban areas, the military and civilian bureaucrats. Along with the dissatisfaction of the people, the criticisms of the opposition and the media became stronger. In response to the criticism, the ruling party took measures which indicated that it had lost control and started to resort to antidemocratic methods. The obstacles which Inonu faced during his tours of the country, increased the censorship of the press and finally, along with the establishment of an "Investigation Commission" a widespread debate began on the regime in Turkey. The university students started demonstrations. The situation became even more tense with the declaration of martial law and eventually led to the military intervention of 27 May 1960.

The 27 May Movement and the Interim Period
To remove the DP from power appeared to be an essential precondition for the solution of the political and economic problems of Turkey and to save the country and democracy, especially for many officers who were sympathizers of Inonu. These officers, of various ranks, who were organized under the title of the National Unity Committee (MBK) started into action in an orderly manner on the morning of 27 May 1960. They removed the DP government and seized power. In the announcement of the revolution, it was stated that the coup was made to save democracy and to prevent fratricidal quarrels, that it was not against any individual or class, and that elections would be held in the shortest period of time and the government would be transferred to the civilians. The communiqué also stated that Turkey would remain as a member of NATO and CENTO.

The overthrown President, Prime Minister, ministers, deputies of the ruling party and the leading administrators of the ruling party, were taken into custody at the War College. General Cemal Gursel, the leader of the coup d'état, assumed the functions of the President, Prime Minister and the Chief of General Staff. The TGNA was dissolved and the MBK took over its legislative functions. A new cabinet, composed chiefly of civilians, was formed on 17 June 1960.

There were, however, differences of opinion among the MBK members. Some of the members wanted to hold elections as soon as possible, while others wanted to hold the election only after radical reforms were made. The members in the second group were taken into custody on 13 November 1960 and were later appointed to various posts abroad.

The MBK established in December of the same year a "Constituent Assembly" responsible for preparing a new constitution and a new election law. The Constituent Assembly, which was formed by the representatives of various institutions, began to work on 5 January 1961. The drafts of the new constitution prepared by academicians, were reviewed in the special commissions of the Assembly and were submitted for discussion. The draft to which the Constituent Assembly gave its final shape after long deliberations, was adopted with a referendum held on 9 July 1961. The MBK left power to the civilians following the elections held on 15 October 1961. In accordance with the Constitution, the 22 members of the MBK entered into Parliament as "Natural Senators" and Cemal Gursel was elected President.

The administrators of the DP, which had been overthrown on 27 May 1960, were tried in the Supreme Justice Council, a special court established at Yassiada by the MBK. The court gave the death sentence to 15 administrators of the DP for "violating the Constitution" and sentenced others to various imprisonment penalties. A total of 12 of the capital punishments were changed into life imprisonment by the MBK. However, Adnan Menderes, the Prime Minister; Fatin Rustu Zorlu, the Foreign Minister; and Hasan Polatkan, the Minister of Finance, were executed. All of the others who were imprisoned were later released through various amnesty initiatives until 1964.

The Active 1960s and the AP Period
The first general election which followed the 27 May revolution revealed an interesting picture. The total of the votes of the Justice Party (AP) and the New Turkey Party (YTP), two parties which claimed to be the continuation of the DP, obtained more than the votes that the DP had obtained in 1957. As for the votes of the CHP, these decreased from 41 percent to 37 percent. This result was an expression of the fact that the political tendencies of the people had not changed and that in fact, the people had reacted to the revolution.