The Constitutional Democratic Party of Japan (CDP) and the Democratic Party for the People (DPP), two opposition parties supported by the Japanese Trade Union Confederation, known as Rengo, should merge, according to former Rengo chief Nobuaki Koga.

Koga, 72, who was selected by the Japanese government Sunday to receive the Grand Cordon of the Order of the Rising Sun, headed the umbrella organization of labor unions in the country when the two parties' predecessor, the Democratic Party of Japan, held the reins of government.

"The fact that they are separated is nonsensical," Koga said in a recent interview. "They should become one."

He also called on CDP leader Yoshihiko Noda to make concessions to DPP leader Yuichiro Tamaki.

Koga's tenure as Rengo chief between 2009 and 2015 overlapped with the 2009-2012 DPJ-led administration. While the change in power from the Liberal Democratic Party was a strongly held wish for Rengo, Koga said that the now-defunct party was naive while governing.

Nobuaki Koga, former head of the Rengo, speaks during an interview in Tokyo last week.
Nobuaki Koga, former head of the Rengo, speaks during an interview in Tokyo last week. | Jiji

"(Members) were opposing what had been decided by the prime minister that everyone chose, and holding each other back," he said.

Both the CDP and the DPP made great strides in the Oct. 27 election for the House of Representatives. Koga said that Noda's decision to take a centrist approach and not to cooperate with the Japanese Communist Party (JCP) enabled the CDP to gather anti-LDP votes.

"(The CDP) had been too close to the JCP before," Koga said, adding that the CDP's latest electoral success was the "Noda effect."

Meanwhile, the former Rengo head expressed a negative view toward Noda's calls for opposition parties to vote for him when a new prime minister is elected in the upcoming special parliamentary session.

"There is no way that party leaders would heed such sudden calls," he said.

The CDP as a whole "lacks people who can bolster ties with other parties behind closed doors," he added.

Koga also slammed Tamaki over the DPP's past decision to vote in support of a government budget bill under the administration of former Prime Minister Fumio Kishida, saying; "It is an act that fully affirms the administration. It's inconceivable."

However, Koga said that the CDP should give in, noting that Tamaki is sticking to his basic policies over nuclear power, national security and the Constitution.

"It is the ironclad rule of organizations that the bigger group makes concessions when cooperating," he added.

Regardless of whether the CDP and the DPP merge, "They should at least field unified candidates for single-seat constituencies in next summer's election for the House of Councilors," Koga said, expressing hope that Noda will spearhead such efforts.