Concerns over losing power grew in the ruling coalition of the Liberal Democratic Party and the New Komeito party after its candidate succumbed to an opposition rival in the Chiba mayoral election Sunday.
"It's a very stinging defeat," a lawmaker who served as a Cabinet minister said, referring to the mayoral race in which Toshihito Kumagai, 31, supported by the Democratic Party of Japan and the Social Democratic Party, beat the ruling parties-backed Kojiro Hayashi, 63.
The election was held following the de facto dismissal of internal affairs minister Kunio Hatoyama on Friday over a Japan Post-related row, prompting a junior LDP lawmaker to say "the bungle of the administration" led to the defeat of Hayashi.
Meanwhile, the victory for Kumagai, which followed victory by a DPJ-backed candidate in the Saitama mayoral race last month, has made the main opposition more confident of winning power in a general election that must be held by fall.
As the DPJ won only two seats in single-seat constituencies in Tokyo, Chiba and Kanagawa prefectures in the 2005 House of Representatives election, party leader Yukio Hatoyama put emphasis on the Chiba mayoral election as a prelude to the next general election.
He visited the city of Chiba twice during the election campaign to appeal for a "change of administration."
The focus is now on whether the ruling bloc can stage counterblows in the Shizuoka gubernatorial race and the Tokyo metropolitan assembly election in July.
In the Chiba mayoral race, Kumagai won 68.7 percent of the nonaffiliated voters, overwhelmingly exceeding 22.8 percent for Hayashi, according to the exit poll by Kyodo News, to which 1,125 voters responded.
Kumagai secured 89.7 percent of the DPJ supporters and 28.9 percent of the LDP affiliates, while Hayashi won 85.7 percent of the New Komeito affiliates and 69.8 percent of the LDP backers.