Tokyo ? Japanese Prime Minister Taro Aso dissolved the powerful lower house of parliament today, setting the stage for national elections next month that could transform the country’s political power structure.

In Japan, the prime minister can decide when to disband parliament and call a general election. Aso had postponed doing so in the hope that his low approval ratings would recover, but after his party was routed in local elections last week he announced the elections for parliament’s lower house would be held Aug. 30.

The country’s political parties quickly shifted into election mode, holding rallies of their lawmakers. Japan’s opposition leader vowed the elections would be “historic.”

The ruling Liberal Democratic Party has maintained a majority in the lower house for most of the past 50 years, but recent opinion polls show the next election could be different, with many voters saying they will support the opposition. This has happened repeatedly in local elections, where the Liberal Democrats have suffered a string of defeats.