Tokyo, Japan (CNN) -- Japan's Social Democratic Party is leaving the coalition government over a dispute regarding the relocation of a U.S. base, the party's leader said Sunday.
Party leader Mizuho Fukushima announced the party's decision at a news conference Sunday. Fukishima, formerly the Minister of Consumers, was let go from Prime Minister Yukio Hatoyama's Cabinet on Friday because she and her party failed to support the government's decision not to move the U.S. Futenma Air Base from Okinawa Island.
While campaigning, Hatoyama promised that he would move the base off Okinawa to ease the burden of the island, which hosts the majority of the United States military presence in Japan, and his Democratic Party of Japan formed a coalition with the Social Democratic Party (SDP). However, Hatoyama decided not to move the base.
The SDP's departure does not threaten the overwhelming majority of the Democratic Party of Japan in the lower house of government, but weakens the party's negotiating power in the upper house. It also threatens Hatoyama's political position ahead of upper house elections, scheduled for this summer.
CNN's Yoko Wakatsuki contributed to this report.