Japan holds an election Sunday for the upper house of parliament that could affect the country's direction. While Prime Minister Shinzo Abe's ruling party is seeking a mandate for his leadership by emphasizing his economic revitalization policies, several opposition parties are coordinating a negative campaign, cautioning voters that a landslide for Abe would give him an upper hand to revise the pacifist post-World War II constitution.

Here are five main points about the election:

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A TWO-THIRDS MAJORITY

A main focus is whether Abe's ruling party and its junior partner Komeito can secure a two-thirds majority — a key benchmark toward constitutional revision — which they already have in the lower house. Media surveys suggest it may be possible with the help of fringe supporters of amendment. Up for grabs in Sunday's vote are 121 seats, or half of the upper house. Abe's coalition and their supporters need to win 78 seats to secure a two-thirds majority of 162. If that happens, they would have the votes in both houses to propose a revision and call a national referendum, though polls suggest voters might not support revision.

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ABENOMICS VS. CONSTITUTION

Abe's party says the focus of the election is the economy and his "Abenomics" program is on track to pull Japan out of deflation. Opposition parties say Abenomics has failed to improve the lives of ordinary people, and urge voters to pay more attention to Abe's security policy giving Japan's military a larger global role, as well as his intention to revise the pacifist constitution. Abe said earlier this year he would make constitutional revision a campaign issue, but the topic is mentioned only as the last item in the party's 26-page campaign pamphlet.

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ABE'S AMBITIONS

As a grandson of Nobusuke Kishi, a former prime minister and ruling party co-founder who despised the U.S.-drafted postwar constitution, rewriting the charter is a long-cherished goal for Abe. While opposition parties mainly focus on a war-renouncing provision, experts say the ruling party's true concern is to restore pre-war traditions and family values centered on the emperor. They add, though, that Abe is pragmatic, and would tackle the economy first. He is expected to compile a major package to make up for the lost tax revenue due to a postponement of a sales tax increase that would have funded child and elderly care support and other projects. A summit with Russian President Vladimir Putin for a possible breakthrough in a territorial dispute that dates to the end of World War II is another political goal for this year. Longer term, there is a growing speculation that Abe, whose second term as party president will expire in two years, may seek to stay in power for a rare third term until 2021, which would give him more time for constitutional revision and the honor of hosting the 2020 Tokyo Olympics.

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OPPOSITION ALLIANCE

The main opposition Democratic Party disappointed the public when it was in power over what was seen as a fumbling response to the 2011 quake, tsunami and nuclear disaster in northeastern Japan. Its rule lasted just over three years, ending in a major defeat in 2012. Following infighting and regroupings, there are eight opposition parties, making it hard for voters to keep track of party names and platforms. Four of the center to liberal-leaning parties — the Democrats, the Communist Party, the Social Democratic Party and the People's Life Party — have formed a rare coalition for this election, running just one unified candidate in each of the 32 single-seat districts to maximize their chances. Their mutual interest is to stop "reckless Abe politics" and block constitutional revision, but a post-election alliance is unclear. Abe harshly criticizes the alliance as lacking principles, since their views differ widely on some policies.

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TEENAGE VOTERS

Sunday's vote is the first nationwide election since the voting age was lowered to 18 from 20, a step aimed at encouraging voting by younger generations, whose turnout has been extremely low. Japan is a fast-aging country where politics has long been taboo at public schools and shunned at homes, while old-style loyalties are key in elections. The addition of 2.4 million younger voters — about 2 percent of Japan's total voter population if they all turn out — is still negligible, experts say. Lowering the voter age was also to keep it in line with a national referendum law, but some experts speculate that a deeper motive is to bring in a younger generations who may be more open to constitutional change compared with senior citizens.

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