The Democratic Party of Japan, Social Democratic Party and Kokumin Shinto (People's New Party) are planning joint campaign pledges for the Aug. 30 election, vowing to boost disposable income and turn the export-oriented economy into one led by domestic demand.

Putting priority on support of the people's livelihoods, sources from the three opposition parties said Friday the group will not raise the 5 percent consumption tax for at least four years and will review the splitup of the nation's postal services into four companies.

The DPJ plans to call on the two other parties to join in a ruling coalition if the opposition camp succeeds in driving the governing Liberal Democratic Party and its coalition partner, New Komeito, from power in the Lower House poll.