Due to its role in emerging victorious and independent from the 1948 Arab–Israeli War, the party won large support in Israel's first elections in 1949, winning 35.7% of the vote and 46 of the 120 seats. Ben-Gurion became Prime Minister and formed a coalition with the United Religious Front, the Progressive Party, the Sephardim and Oriental Communities and the Democratic List of Nazareth. A notable piece of legislation enacted during Mapai's first term in office was an educational law in 1949 which introduced compulsory schooling for all children between the ages of 5 to 14. Mapai's years in office also witnessed the passage of the National Insurance Act of 1953 and the Social Welfare Service Law of 1958, which authorised a broad range of social welfare programmes, including special allowances for large families, workers' compensation provisions, maternity insurance, and old age and survivors' pensions. In the second elections in 1951 Mapai increased its vote to 37.3% despite the country's economic problems. Ben-Gurion again formed the government with the support of Mizrachi, Hapoel HaMizrachi, Agudat Yisrael, Poalei Agudat Yisrael and the three Israeli Arab parties associated with Mapai, the Democratic List for Israeli Arabs, Progress and Work and Agriculture and Development. However, he shocked the nation by resigning on 6 December 1953 in order to settle in the small Negevkibbutz of Sde Boker, and was replaced by Moshe Sharett. The 1955 elections saw a drop in the party's support to 32.2%, though still well ahead of the second-placed Herut. Ben Gurion returned as Prime Minister, and formed a coalition with the National Religious Front, Mapam, Ahdut HaAvoda, and the three Israeli Arab parties, the Democratic List for Israeli Arabs, Progress and Work and Agriculture and Development. Later the Progressive Party was also added. In contrast to the previous one, the 1959 election saw a surge in support, as the party recorded its best electoral performance, taking 38.2% of the vote and 47 seats. Ben-Gurion again invited the National Religious Party, Mapam, Ahdut HaAvoda, the Progressive Party and the three Israeli Arab parties, Progress and Development, Cooperation and Brotherhood and Agriculture and Development to form the coalition. The inquiry into the Lavon Affair which brought down the government in 1961 probably contributed to the party's relatively poor performance in the elections in the same year, as it picked up only 34.7% of the vote and 42 seats. Although Ben-Gurion formed a strong coalition with the National Religious Party, Ahdut HaAvoda, Agudat Yisrael Workers, Cooperation and Brotherhood and Progress and Development, two events during the fifth Knesset led to Mapai's reducing dominance. Firstly, Ben-Gurion resigned as head of the party citing personal reasons, though in reality he was upset at a perceived lack of support from colleagues. He set up a new party, Rafi, taking with him seven other Mapai members. Secondly, the two major right-wing opposition parties, Herut and the Liberal Party had merged into Gahal. This meant by the end of the Knesset session, Mapai had only 34 seats to Gahal's 27. The party's response to the unprecedented strength of the opposition was to seek support from other parties with similar ideologies. The result was an alliance with Ahdut HaAvoda to form the Labor Alignment before the 1965 election. The new party won 36.7% of the vote and 45 seats, and comfortably beat Gahal. On 23 January 1968 Mapai, Ahdut HaAvoda and Rafi merged into the Israeli Labor Party and ceased to exist as individual entities.
