TOKYO - Japanese voters cast ballots Sunday in an upper house election, with Shinzo Abe's ruling bloc looking to protect its majority and keep on track plans to amend the country's pacifist constitution.
Abe, 64, who is on course to become Japan's longest-serving prime minister, is also hoping to shore up his mandate ahead of a crucial consumption tax hike later this year, along with trade negotiations with Washington.
Opinion polls suggest his Liberal Democratic Party (LDP) and its coalition partner Komeito are likely to win a majority, mostly because of a lackluster opposition.
Sunday's vote is for half the seats in the House of Councilors - the less powerful house of parliament - and polling stations across the country open at 7 a.m. (2200 GMT Saturday).
The vote outcome is expected to become clear shortly after the polls close at 8 p.m., with pollsters suggesting turnout could be lower than 50 percent, significantly less than usual.
'Disarray' in opposition camp
Abe's ruling coalition is forecast to win a solid majority of the 124 seats contested in the election, according to pre-election surveys.
The two parties control 70 seats in the half of the chamber that is not being contested, meaning the projections put them on track to maintain their overall majority in the body.
"Abe's strength is largely based on passive support resulting from disarray in the opposition camp and a lack of rivals," Shinichi Nishikawa, professor of political science at Meiji University in Tokyo, told AFP.
A win means Abe should be able to stay in power until November, when he will break the service record of Taro Katsura, a revered politician who served three times as premier between 1901 and 1913.
During campaigns, Abe's ruling coalition has sought to win voter support for a rise in the nation's consumption tax to 10 percent later this year as part of efforts to ease swelling social security costs in the "ultra-aged" country.
Abe is also hoping that his coalition and a loose group of conservatives from smaller opposition parties can grab a two-thirds majority in the upper house, giving him the support to move ahead with plans to amend the constitution's provisions on the military.
"This is an election to decide whether to pick parties who take responsibility for firm discussions on the constitution," Abe told voters in a campaign speech earlier this month.
Abe vowed to "clearly stipulate the role of the Self-Defense Forces in the constitution," which prohibits Japan from waging war and maintaining a military.
The provisions, imposed by the U.S. forces after World War II, are popular in the public at large, but reviled by nationalists like Abe, who see them as outdated and punitive.
Local media predict that forces in favor of revising the constitution, led by Abe's LDP, are likely to win close to 85 of the seats being contested, giving them a "supermajority" in the chamber.
"Since the ruling coalition is widely expected to win the election, attention is now focused on whether the pro-revision forces can win a two-thirds majority," Nishikawa said.
But even if Abe secures it, any constitutional revision also requires approval in a national referendum, a result that is far from guaranteed.