However, the Katayama government collapsed due to the rebellion of communists in the party. The party continued the coalition with the Democrats under Prime Minister Hitoshi Ashida; but the cabinet was engulfed by the Shōwa Denkō scandal, the largest corruption scandal during the occupation, allowing Shigeru Yoshida and the Liberal Party to return to government. In the period following the end of World War II, the Socialists played a key role in the drafting of the new Japanese constitution, adding progressive articles related to issues such as health, welfare and working conditions. The party was split in 1950–1951 into the Rightist Socialist Party, consisting of socialists who leaned more to the political centre; and the Leftist Socialist Party, formed by hardline left-wingers and socialists. The faction farthest to the left formed a small independent party, the Workers and Farmers Party, espousing Maoism from 1948 to 1957. The two socialist parties were merged in 1955 and joined the Socialist International that year. The new opposition party had its own factions, although organised according to left-right ideological beliefs rather than what it called the feudal personalism of the conservative parties. In the 1958 general election, the party gained 32.9 percent of the popular vote and 166 out of 467 seats. This was enough result to block the attempt of constitutional amendment by the Kishi Nobusuke-led government. However, the party was again split in 1960 because of internal conflicts and the assassination of Inejiro Asanuma and the breakaway group (a part of the old Right Socialist Party of Japan, their most moderate faction) created the Democratic Socialist Party, although the party was preserved. After that, the party's percentage of the popular vote and number of seats gradually declined. However, the party performed well on a local level and by the 1970s many areas were run by SDPJ mayors and governors (including those who were endorsed by the SDPJ), who introduced new social programmes. In 1977, some members, led by Saburō Eda (江田三郎) and Hideo Den (田英夫) respectively, left the JSP, and a minor party called Socialist Democratic Federation (社会民主連合) were formed by them in 1978. In the double election of July 1986 for both Diet houses, the party suffered a rout by the Liberal Democratic Party (LDP) under Yasuhiro Nakasone and its seats in the lower house fell from 112 to an all-time low of eighty-five and its share of the vote from 19.5 percent to 17.2 percent.