The main opposition Democratic Party of Japan approved on Friday slight changes to its leadership following a major setback in Sunday's upper house election, with Banri Kaieda remaining as party leader.
While seeking support from member lawmakers, Kaieda suggested he would step down as party president in one year's time if he does not successfully reinvigorate the DPJ, which lost more than half of its contested seats in the recent House of Councillors election.
"Unfortunately, my seven months in office have not led to any achievement so far," Kaieda told a general meeting of the party's Diet members. "I believe that in about one year's time from now, I will not be asking you to allow me to remain the DPJ's representative if I have not produced any tangible result."
Kaieda did not specify any conditions for him to stay on at the party's helm, only indicating that he wants to lead the party to victory in the unified local elections in the spring of 2015. There will be no national election in Japan until 2016 unless the House of Representatives is dissolved.
At the meeting, the DPJ members also approved the appointment of Acting President Akihiro Ohata as new secretary general, succeeding Goshi Hosono, who stepped down to take responsibility for the defeat in the House of Councillors election.
The outcome of the election, which gave Prime Minister Shinzo Abe's ruling bloc full control of parliament, is widely expected to trigger a realignment in opposition parties.
Kaieda did not deny such a possibility, saying, "It is most important that the DPJ will act at the center" of any political developments.
Holding an executive meeting earlier in the day, the DPJ also decided to suspend the membership of former Prime Minister Naoto Kan for three months for his support of an independent candidate in the upper house election in defiance of a party decision.
Kaieda initially proposed expelling the former leader from the party, but dropped the idea in the face of objections to such heavy punishment after Kan apologized.
Kan supported a candidate in the Tokyo constituency even after the DPJ, which initially planned to field two candidates there, withdrew its backing two days before official campaigning started, in view of the slim chance of securing two seats there. Neither candidate was elected.
The executive board also adopted a letter of protest against Yukio Hatoyama, another former prime minister from the party, for his repeated remarks in favor of China on a bilateral row over a group of islands in the East China Sea. Hatoyama has already left the party.
"Such irresponsible remarks that will damage national interests are very regrettable," the letter said.
Hatoyama has said it was unavoidable for China to state that Japan had stolen the uninhabited islands, controlled by Tokyo but claimed by Beijing, contradicting the Japanese government's stance that there is no dispute over the islets.
The DPJ held power after winning the 2009 general election and before being trounced by Abe's Liberal Democratic Party in last December's lower house contest.