when the current constitution took effect in 1947, the first House of Councillors election was held several days apart from the 23rd House of Representatives election. Only in 1980 and 1986, general and regular election coincided on the same day because the House of Representatives was dissolved in time for the election to be scheduled together with the House of Councillors election in early summer. Vacant district seats in both Houses are generally filled in . Nowadays, these are usually scheduled in April and October as necessary. Vacant proportional seats in both Houses and district seats in the House of Councillors that fall vacant within three months of a regular election are filled by : the highest ranking candidate on a proportional list or in the electoral district who was not elected and is not disqualified takes the seat. Disqualifications may, for example, happen if a candidate for the House of Councillors runs for the House of Representatives or vice versa, or after a violation of campaign laws. For many years, Japan was a one party dominant state until 1993 with the as the ruling party. It won a majority of the popular vote in House of Representatives general elections until the 1960s. It lost the majority of seats in 1976 and 1979, but continued to rule without coalition partners with the support of independent Representatives. After the 1983 election when it again lost the majority, it entered a coalition for the first time – with the . In 1986, the coalition ended as the LDP won a large majority of seats and even came close to a majority of votes. The party suffered its first clear electoral defeat in the 1989 House of Councillors regular election when it lost the upper house majority and had to face for the first time a where passing legislation depends on cooperation with the opposition. The LDP was out of government for the first time in 1993 after Ichirō Ozawa and his faction had left the party and the opposition parties united in an anti-LDP coalition, but then soon returned to the majority in 1994 by entering a coalition with its traditional main opponent, the . The 2009 House of Representatives elections handed the first non-LDP victory to the . According to a survey by Yomiuri Shimbun in April 2010, almost half of Japanese voters do not support any political parties due to