With the approach of the summer Upper House election, several new parties are vying for voters disenchanted with the Democratic Party of Japan, which swept to power last year on the promise of change but became mired in money scandals and accusations of poor leadership.

Four small parties, mainly made up of defectors from the Liberal Democratic Party, are gearing up to win the deciding vote in the Upper House, where the DPJ-led ruling bloc clings to a slim majority.

If the DPJ-led coalition fails to win the hearts of swing voters and hold onto its majority in the chamber, the minor parties will gain a greater say in passing government-sponsored bills, experts say.