The Democratic Party of Japan says that if it comes to power it will confront the United States on key military and diplomatic issues but still regard it as the nation's most important ally.
The DPJ is ahead in the opinion polls and is expected to topple the Liberal Democratic Party in the Aug. 30 general election.
Japan largely sets its own course in financial matters but over the decades has followed Washington's lead in broad areas of military and foreign policy. It relies on the U.S. for nuclear deterrence and hosts tens of thousands of American service members, as well as military aircraft and warships.