The main opposition Democratic Party of Japan on Wednesday asked former DPJ leader and Prime Minister Naoto Kan to leave the party for supporting an independent candidate in Sunday's House of Councillors election in violation of party policy, DPJ sources said.
DPJ leader Banri Kaieda met with Kan in the morning and asked him to leave. If Kan refuses, the party will likely expel him, according to the party sources.
In the crucial Tokyo constituency, the DPJ fielded only one candidate after revoking its endorsement of another candidate only two days before official campaigning kicked off July 4 due to the slim likelihood of securing two seats in the capital.
But Kan, one of the founding members of the party, opposed the decision and backed Masako Okawara, who ran as an independent after losing the DPJ's endorsement, during the election campaign.
Neither she nor Kan Suzuki, the DPJ's sole candidate in Tokyo, won a seat.
The DPJ held a meeting of its executives to discuss how to recover from its devastating defeat in Sunday's election. Secretary General Goshi Hosono has decided to step down in August to take the blame.
Kan was prime minister when a massive earthquake and tsunami triggered a nuclear crisis at a nuclear power plant in Fukushima Prefecture, and later became an advocate of abolishing nuclear power plants in Japan.
He was forced to step down in 2011 amid criticism of his handling of the nuclear crisis and has been supreme advisor to the DPJ.
In a similar development humiliating to the DPJ, Kaieda is also expected to consider punitive action against former Prime Minister Yukio Hatoyama for repeated remarks interpreted as siding with China over the Senkaku Islands in the East China Sea, the sources said.
But since Hatoyama has already left the party, the only option for the DPJ is to retroactively expel him.
Hatoyama said in an interview with Hong Kong's Phoenix Television in June that it was unavoidable for China to state that Japan had stolen the uninhabited islands, administered by Japan but claimed by China.
His claim runs contrary to Tokyo's repeated stance that there is no territorial dispute over the Senkakus, which Japan considers an inherent part of its territory in terms of history and international law.
The DPJ has been in disarray since Sunday's election that gave Prime Minister Shinzo Abe and his Liberal Democratic Party a vote of confidence for his economic policy prescriptions dubbed "Abenomics."
The opposition party won only 17 seats, the lowest on record since it was formed in 1998. Some within the party call for an early election to pick a new leader, but Kaieda is expected to stay on as president to revive the party, which held power from 2009 to 2011.