The secretary general of the main opposition Democratic Party of Japan, Goshi Hosono, said Tuesday he will step down in late August to take the blame for the party's major setback in Sunday's House of Councillors election.
Hosono expressed his intention to quit on Monday following the party's worst-ever showing in an upper house election and rejected requests by DPJ leader Banri Kaieda and other executives to stay on.
"It's not possible that nobody should take responsibility" for the election result, Hosono told reporters at DPJ headquarters. "We need to carry out transformative reforms" for the party's rebirth.
In the election, the DPJ won only 17 seats, the fewest since the party was formed in 1998.
Hosono also said he will quit because of the failure of a DPJ candidate to win a seat in the Tokyo constituency. Hosono had played a role in the party's decision to revoke its endorsement of another candidate due to the slim likelihood of securing two seats in the capital.
Before stepping down in late August, Hosono said, he will handle the party's punitive measures against former DPJ leader and Prime Minister Naoto Kan, who supported independent Masako Okawara in the Tokyo district during the election campaign.
Okawara ran as an independent after losing the DPJ's endorsement. Neither she nor Kan Suzuki, the only DPJ candidate in Tokyo, won a seat.