Official campaigning is set to get under way Thursday for an upper house election later this month that will be a key test of Prime Minister Shinzo Abe's leadership over the past seven months.
Abe, who heads the Liberal Democratic Party, has set the goal of wresting control of the House of Councillors from the opposition parties in the July 21 election and solidifying his power base to achieve key policy objectives such as reviving the economy and revising the nation's pacifist Constitution.
The opposition camp is struggling to erode relatively high support rates for Abe's government, launched in December after the LDP trounced the Democratic Party of Japan in a general election and returned to power.
Half of the 242 seats in the upper house are up for grabs every three years under a combination of constituencies and proportional representation. Around 430 candidates are expected to vie for the 121 seats at stake.
The LDP and its junior coalition partner, the New Komeito party, need to win a total of 63 seats to secure a majority, as they already hold 59 seats that will not be contested this time.
The ruling camp has an overwhelming majority in the more powerful House of Representatives. But lacking control in the upper chamber makes it difficult for the government to push its policy agenda through the Diet.
Abe was forced to step down as prime minister in 2007 amid political deadlock in the divided Diet that stemmed from his defeat in an upper house election the same year.
His economic policy drive, dubbed "Abenomics," to turn nearly two decades of deflation into mild inflation will be one of the focuses in the election. Abe has pointed to a recovery in Japanese stock prices as evidence his policies are working.
Opposition parties, meanwhile, have highlighted concerns about possible downsides of Abenomics such as higher consumer prices at a time when wage increases have yet to be implemented by many companies.
Party leaders will hit the streets later in the day to call for voters' support at the launch of the 17-day campaign period.
Abe is scheduled to deliver a stump speech in Fukushima Prefecture in the morning, where he will highlight the government's efforts to rebuild northeastern Japan following the March 2011 earthquake and tsunami that triggered a nuclear crisis at the Fukushima Daiichi plant.
Candidates and parties are allowed for the first time to employ e-mail and social networking sites for their campaigning, after the Diet enacted legislation in April to lift the ban on online campaigning in an attempt to counter political apathy, especially among the youth.