The Mainichi Shimbun has analyzed voting behavior among constituents with no party affiliation based on exit polls it conducted between 2005 and 2009 and similar polls carried out by Kyodo News between 2010 and 2014, shedding light on the force such voters could bring to next month's election.
In the 2005 House of Representatives election called by then Prime Minister Junichiro Koizumi to seek a mandate for his highly controversial policy agenda to privatize the country's postal services, 33 percent of nonaffiliated voters said they had voted for the Liberal Democratic Party (LDP). The LDP, whose organized support outweighed that of its rivals, scored a landslide victory as it split the votes from the independents with the then Democratic Party of Japan (DPJ).
Contrastingly, in the 2007 House of Councillors election and the 2009 lower house election in which the DPJ won, 51 percent and 52 percent of nonaffiliated voters said they had voted for the DPJ, respectively. The LDP garnered only about 10 percent of votes from the independents in both of the two national elections. The exit polls underscore the fact that the DPJ was buoyed by nonaffiliated voters.
In the 2012 lower house election held after Your Party (now disbanded) and the Japan Restoration Party (currently Initiatives from Osaka) emerged as up-and-coming opposition parties as a result of the sputtering of the then DPJ, nearly 40 percent of votes from independent voters went to the two new opposition parties that called themselves the "third force" in Japanese politics. Similar trends were also seen in the 2013 upper house election and the 2014 lower house contest.
Nonaffiliated voters have more or less consistently accounted for about 20 percent of all voters in a total of seven national elections called since 2005 when a lower house election was held.
In the April 2016 lower house by-election in the Hokkaido No. 5 district, viewed by each political party as a prelude to the upcoming upper house contest, 70 percent of nonaffiliated voters said they had voted for an independent candidate backed by opposition parties, according to exit polls conducted by the Mainichi Shimbun and Hokkaido Broadcasting Co. Although the independent candidate lost in the election, the support from nonaffiliated voters is believed to have been a key factor that enabled her to fight against a rival LDP candidate, who had overwhelming organized support. After seeing the election results, a senior LDP official said at that time, "We will be in big trouble if independent voters are to support the opposition camp in the upper house election."
In a nationwide opinion poll conducted by the Mainichi on June 18 and 19, 57 percent of nonaffiliated voters said it would be "better" for the opposition bloc to increase its seats in the July 10 upper house election, while only 20 percent of them said it would be "better" for the ruling bloc to increase its seats.