Renho, a front-runner in the Democratic Party's upcoming leadership election, vowed Tuesday to rebuild the biggest opposition force's flagging popularity and prove to voters it is capable of more than just picking holes in Prime Minister Shinzo Abe's policies.

If she wins the Sept. 15 election, Renho, 48, would be the latest in a series of women elevated to leadership positions in Japan's male-dominated world of politics, following Tokyo Gov. Yuriko Koike and newly appointed Defense Minister Tomomi Inada.

Expectations are also high that her leadership would spruce up the Democratic Party's tattered image.