As more than 380 candidates took to the streets across the nation, pleading for votes from vans outside train stations and shopping arcades, Abe opened the campaign with a pledge to proceed with his "Abenomics" plan to revive the economy and pull the country out of a slump.
"The biggest topic of this election is economic policies," Abe told a crowd in Kumamoto, a southern city struck by deadly earthquakes in April. "This is an election in which we decide whether to return to that dark doldrums or not."
The pro-business ruling party is hoping for a show of support for Abe's economic program, while the opposition is criticizing his efforts to have Japan take a bigger global security role and has warned of his party's ultimate goal of wanting to rewrite Japan's pacifist constitution to reflect the new security policy.
"We will stop the reckless Abe politics and change its course," Katsuya Okada, head of the main opposition Democratic Party, said in a speech in Kofu in central Japan. "We will bring in a new wind into Japanese politics."
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Old-style loyalties are generally crucial in Japanese elections, so the addition of 2 million younger voters, about 2 per cent of the total voter population if they all turn out will be closely watched, although campaign platforms largely catering to Japan's aging population are turning away young voters and experts say the impact of the expanded voting age will be minimal.
Opposition groups want to keep the ruling bloc from gaining ground in the upper house, where they have a majority but are short of the two-thirds mark.
The splintered opposition sorely disappointed the public over what was widely seen as its fumbling response to the 2011 quake, tsunami and nuclear disaster in northeastern Japan when it was in power.