Constitutional Democratic Party of Japan leader Yukio Edano is facing pressure from colleagues in the party to take responsibility for its weaker-than-anticipated performance in the July 21 Upper House election.

In the triennial Upper House poll, in which 124 seats were up for grabs — or about half of all seats in the chamber — the main opposition party won 17 seats. Nine of its pre-election seats were contested.

“Thanks to great efforts by everyone, we nearly doubled our seats,” Edano emphasized at a meeting of party executives on Thursday. “We have to work even harder so that voters choose a change of government in the next election for the House of Representatives,” the all-important lower chamber.

Some media reports had suggested the CDP could gain 20 or more seats, but it failed to win seats in the Kyoto and Osaka prefectural districts, falling behind the smaller Japanese Communist Party.

Under the proportional representation system, the CDP secured eight seats, but the other 14 people on its candidate list were unsuccessful, including a former member of pop group Morning Musume.

One reason for the CDP’s lackluster showing is believed to be that some voters critical of the administration led by Prime Minister Shinzo Abe, head of the Liberal Democratic Party, opted to vote for Reiwa Shinsengumi, a new group launched by actor-turned-politician Taro Yamamoto.

The new political group attracted voters by presenting clear-cut policies including the abolition of the consumption tax. The CDP advocated calling off a planned hike in the tax set for October.

“The tailwind we received (after the CDP was launched) about two years ago has gone away,” a source in the party lamented.

“Media reports say the CDP advanced in the Upper House poll, but my feeling is that we lost in effect,” Koichi Yamauchi, the party’s deputy policy head, said in a blog post.

“We need to squarely face the reality that we are far from taking power and to hold serious discussions within the party,” he wrote, urging the party leadership to review its election strategy.

In particular, the Edano-led leadership’s decision to field a candidate against a senior Democratic Party for the People member in Shizuoka Prefecture drew criticism from CDP members.

The CDP, the DPFP and two other opposition parties cooperated in many electoral districts in the Upper House poll.