Three political parties were active in the Middle Congo before the territory achieved its independence. Of these, the most important proved to be the Democratic Union for the Defense of African Interests (Union Démocratique de Défense des Intérêts Africain— UDDIA), founded by Abbé Fulbert Youlou. The UDDIA received 64% of the popular vote and won 51 of the 61 seats in the National Assembly elected in June 1959. Following the resignation of President Youlou and the dissolution of the Assembly in 1963, all political parties were banned. On 2 July 1964, the National Movement of the Revolution (Mouvement National de la Révolution—MNR), led by President Massamba-Debat, was officially established as the country's sole political party. A power struggle between the People's Militia and the army, tribal rivalries, and other conflicts led to Massamba-Debat's resignation in September 1968. The army commander in chief, Marien Ngouabi, then became head of state.
The Congolese Labor Party (Parti Congolais du Travail— PCT), created in December 1969 to succeed the MNR, had been based on the principles of Marxism-Leninism and democratic centralism. But at its 1990 conference, the PCT abandoned this ideology. The 1979 constitution recognized the PCT as the sole party: all other political parties and any political activity outside the PCT were illegal. In the National Assembly elections of 8 July 1979, all candidates were PCT members.
After his assassination on 18 March 1977, Ngouabi was succeeded by Col. Joachim Yhombi-Opango, and in March 1979 by Col. Denis Sassou-Nguesso, who was reelected in July 1984.
The 1991 National Conference led to an interim government and multiparty elections in 1992. Continual shifts in parties and in coalitions of parties have taken place since. The most significant of the many parties is the Democratic and Patriotic Forces (FDP), which is an alliance of six parties including that of Sassou-Nguesso's Union for National Renewal. Others include the Pan-African Union for Social Development (UPADS), the party of former President Lissouba. Lissouba's former coalition included the Rally for Democracy and Development (RDD) and was opposed by the PCT and the Union for Democratic Renewal (URD).
Following the 1993 elections, the National Assembly was broken down as follows: UPADS, 47 seats; Congolese Movement for Democracy and Integral Development, 28; PCT, 15; Association for Democracy and Social Progress, 10; RDD, 6; Union of Democratic Forces, 3; others, 14; independents, 2. Elections due in July 1997 were delayed until the new constitution was adopted. The civil war and fighting between 1997 and 1999 restricted party activity. Sassou-Nguesso allowed some politicians from the former government to return and resume political activity in 1999, but he banned former president Lissouba and Prime Minister Kolelas. Indeed Kolelas and former interior minister Col. Philippe Bikinkita were sentenced to death in absentia on 5 May 2000 in the Brazzaville criminal court for illegal detention, false imprisonment, and torture. The National Transitional Council included representatives of opposition parties and members of civil society, but the NTC composition was criticized by some as being government-controlled and not being broad-based enough for a fair representation of Congo's 15 political parties.
In the absence of any serious competition, Sassou-Nguesso's coalition easily won the 2002 presidential and parliamentary elections.