The opposition Party of Hope, still stinging from a disappointing performance in last month's general election, selected lower house lawmaker Yuichiro Tamaki on Friday to serve as co-leader alongside its founder, Tokyo Gov. Yuriko Koike.

With Koike not holding a seat in the Diet, Tamaki will lead the parliamentary activities of the Party of Hope, which had vowed to topple Prime Minister Shinzo Abe's Liberal Democratic Party before falling well short of the goal in the Oct. 22 election.

"We must seriously and humbly face up to what happened and ask ourselves why we lost...I think it was up to each and every one of us," Tamaki told the assembled lawmakers.

"I want to work with all of you to grow this Party of Hope into a party that can open up a future for Japan," he said.

Tamaki, a 48-year-old fourth-term House of Representatives member, defeated his sole rival Hiroshi Ogushi by winning 39 of the 53 votes of the party members from both chambers of parliament. Ogushi, 52, is a fifth-term lower house lawmaker who served as policy chief of the struggling Democratic Party. Koike herself did not cast a ballot Friday.

Tamaki, also a former Democratic Party member, will be tasked with expanding the strength of the fledgling party and required to collaborate with Koike, who has expressed her willingness to concentrate on managing the metropolitan government. The co-heads' tenure runs through September 2020.

The Tokyo governor established the national political party weeks before the general election, taking aim at Abe's LDP, which ended up achieving a landslide victory.

The Party of Hope endorsed 235 candidates nationwide in the 465-seat election, but managed to secure just 50 seats. Besides them, three House of Councillors lawmakers, whose seats were not contested in the election, belong to the party.

The fledgling party absorbed many Democratic Party members who had pledged to fall in line with Koike's conservative views on such contentious issues as national security and amending Japan's pacifist Constitution. Tamaki and Ogushi were among them.

After declaring their candidacies in the leadership contest, Tamaki expressed his eagerness to back up Koike's positions, including promoting debates over revising the Constitution, while Ogushi, who is not against debating constitutional revisions, said he is opposed to an amendment to the document's war-renouncing Article 9.

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