Politically, the treaty gave a greater role to national governments than had the earlier ECSC treaty, though it did provide for the EEC to become more supranational as economic integration progressed.
In response to the EEC, the United Kingdom and six other non-EEC countries formed the European Free Trade Association (EFTA) in 1960. In 1961, with the EEC's apparent economic success, the United Kingdom began negotiations towards membership. In January 1963, however, the French president Charles de Gaulle vetoed British membership, particularly because of its close ties to the United States. De Gaulle vetoed British admittance a second time in 1967.

Creation of the EC

The basic economic features of the EEC treaty were gradually implemented, and the three communities (the EEC, the ECSC, and Euratom) merged in July 1967 under one set of institutions, the European Community. No progress was made on enlargement of the EC or on any other new proposals, however, until after De Gaulle resigned as president of France in May 1969. The next French president, Georges Pompidou, was more open to new initiatives within the EC.
At Pompidou's suggestion, a summit meeting of the leaders of the member states was held in The Hague in December 1969. This summit paved the way for the creation of a permanent financing arrangement for the EC, the development of a framework for foreign-policy cooperation among the member nations, and the opening of membership negotiations with the United Kingdom, Ireland, Denmark, and Norway.

Expansion of the EC

In January 1972, after nearly two years of negotiations, treaties of accession were signed to admit the four applicant countries on January 1, 1973. The United Kingdom, Ireland, and Denmark joined as scheduled; however, in a national referendum, Norway voted against membership.
In the United Kingdom, opposition to EC membership continued. After the Labour party regained power in 1974, it carried out its election promise to renegotiate British membership conditions (particularly financial ones); the renegotiation resulted in only marginal changes, but it created a period of uncertainty within the EC. A divided Labour government endorsed continued EC membership and called a national referendum on the issue for June 1975. Despite strong opposition from some groups, the British people voted for continued membership.
In 1979 and 1980, the British government, claiming that the value of its contributions far exceeded the value of benefits received, again attempted to change its terms of membership. The conflict was resolved during the spring of 1980 when several members agreed to pay a greater share of the EC costs.