TOKYO -- The Japanese ruling coalition added to its upper house majority in Sunday's election, with Prime Minister Shinzo Abe and parties that back his goal of revising the constitution reaching the two-thirds supermajority required to start the process.

The ruling bloc exceeded Abe's target of securing a majority of the 121 contested seats. His Liberal Democratic Party and junior partner Komeito have taken at least 70 together. The prime minister has strengthened his grip on power, winning the last four major national elections. And he has gained a mandate to carry on with his economic policies and delay the consumption tax hike.

A motion to revise the constitution needs 162 votes in the 242-seat upper house. The four parties seeking to alter the constitution -- the LDP, Komeito, the Initiatives from Osaka party and the Party for Japanese Kokoro -- secured more than the 74 seats that would give them a supermajority when combined with like-minded independents and existing seats not up for election. In the lower house, the ruling coalition already had the required two-thirds majority.

The LDP proved strong in the 32 single-seat upper house districts, which held the key to this election. It won 21, mainly in western Japan.

The Democratic Party, the Japanese Communist Party, the Social Democratic Party and the People's Life Party had agreed to field a single candidate in each single-seat district, rallying around a goal of denying a supermajority to the four parties in favor of changing the constitution. This led to races that were effectively one-on-one battles with LDP candidates -- a strategy yielding only limited success.

Abe's party also fared well in two- to six-seat constituencies. The LDP won in each of the multiseat districts where the party fielded just one candidate. In cases where it backed two contestants, both won in Tokyo and Chiba prefectures. Two prevailed in Kanagawa, where the party threw its official support to the second candidate Saturday.

The opposition Democratic Party split seats with the LDP in the two-seat districts of Ibaraki, Shizuoka, Kyoto and Hiroshima prefectures. But it faltered in single-seat constituencies and lost all its seats in the four-seat district of Osaka and the three-seat district of Hyogo. Overall, the Democrats apparently went from 45 contested seats before the election to the lower 30s.

The LDP also showed strength in seats awarded through proportional representation. The Democratic Party won more than the seven it had taken in 2013 when suffering a crushing defeat as the Democratic Party of Japan, but fell short of the 16 won in 2010.

The Communist Party and Initiatives from Osaka secured more seats than before the election. The former won a seat in the six-seat Tokyo district, while the latter gained in its home territory of Osaka and Hyogo. The Social Democratic Party gained one seat via proportional representation. The New Renaissance Party and the Party for Japanese Kokoro did not win any seats.

This marked the first national election in which 18- and 19-year-olds were eligible to vote.

(Nikkei)