The opposition Democratic Party is confident ahead of general elections
Japan's opposition Democratic Party (DPJ) has won another local election, with a landslide, ahead of general elections that must be held this year.
The city of Chiba, near Tokyo, is the third big municipality win for the DPJ in the past two months after both Nagoya and Saitama.
The Liberal Democratic Party has ruled Japan almost unchallenged for 50 years.
With Japan in the middle of a recession, the LDP has faced criticism for offering weak leadership.
Prime Minister Taro Aso lost a cabinet ally on Friday when Internal Affairs Minister Kunio Hatoyama resigned.
He was the third minister to quit since Mr Aso took office last September.
In the latest election, for mayor of Chiba, the DPJ backed the young, 31-year old Toshihito Kumagai, against the incumbent LDP candidate, 63-year old Kojiro Hayashi.
Public opinion polls have shown the Democrats well ahead of the LDP in the run-up to a general election that must be held by October and that many expect to be held in August.
The latest election win for the Democratic Party had "deepened a sense of crisis" in the ruling coalition ahead of the general election, Jiji Press news agency said.
A Democratic Party victory in the general election would end more than five decades of almost unbroken rule by the conservative LDP.