Poll: Japan’s LDP Likely to Lose Seats in Proportional Representation Segment; DPFP, Sanseito Expected to Gain More Seats in Upper House

By Koji Sobata and Daiki Misawa / Yomiuri Shimbun Staff Writers

20:00 JST, July 5, 2025

The Liberal Democratic Party could lose a significant number of seats in the proportional representation segment of the upcoming House of Councillors election, according to a Yomiuri Shimbun survey.

In the previous upper house election in 2022, the ruling party won 18 seats in the segment. This time, 50 proportional representation seats will be up for grabs.

The survey, which was conducted to see how the early stage of campaigning was going for the July 20 election, showed that the Constitutional Democratic Party of Japan is expected to secure around the same number of seats as in the previous election. Two other opposition parties — the Democratic Party for the People and Sanseito — are likely to gain more seats.

Prime Minister Shigeru Ishiba, who also serves as LDP president, solicited support while hinting at the LDP’s difficult campaign situation.

“Even though we won’t get applause, we will fight with all our might in the election by taking responsibility for the future of this country to the end,” he said during a campaign speech in Wajima, Ishikawa Prefecture, on Friday.

The LDP is expected to maintain its top position in the proportional representation race. However, the party could see the number of its seats in the segment fall to the same level as its record low of 12 in the 2010 election.

According to the survey, the LDP has solidified support from more than 70% of its supporters for the upcoming election. However, it has cemented support from less than 50% of respondents who support the Cabinet.

The survey results are unclear as to whether Komeito, the LDP’s ruling coalition partner, can maintain the six seats it won in the previous election. Since the current electoral system, which combines constituency and proportional representation races, was introduced in 1983, Komeito has never seen the number of its proportional representation seats fall below six.

If the LDP and Komeito are forced into a ruling minority in the upper house, like in the House of Representatives, the management of government could become even more difficult.

“Conservative votes are moving away [from the LDP] because there is insufficient communication from the prime minister,” said a senior LDP official.

Opposition parties are poised to challenge the Ishiba administration’s political stance during the campaign, hoping to garner votes in the proportional representation segment from people critical of the administration.

According to the survey, the CDPJ is likely to win between six and nine seats in the segment. The figure is on par with the seven seats it won in the previous election.

However, only slightly more than 10% of respondents who disapproved of the Cabinet supported the CDPJ.

In a campaign speech in Kumamoto City on Friday, CDPJ President Yoshihiko Noda referred to the issue of the provisional gasoline tax.

“As the basis for taxation no longer exists, it is only natural to abolish the tax,” Noda said. “However, the LDP is getting in the way of that.”

Meanwhile, Sanseito has increased its presence. The party looks to secure between four and nine seats, a significant increase from the one seat it won in the previous election.

In the survey, Sanseito ranked No. 2 among respondents who cited “diplomacy and security” and “constitutional amendment” as key policy issues, following the LDP. Sanseito may be an alternative for conservative voters.

The DPFP, which gained more seats in last year’s lower house election, won three proportional representation seats in the previous upper house election. The party appears on track to double its number of seats.

In the survey, the DPFP ranked No. 1 among younger voters, with more than 20% of respondents aged 18 to 39 backing it.

Reiwa Shinsengumi, which won two proportional representation seats in the previous election, could gain two to four seats in the segment. The Japan Innovation Party is likely to see the number of its seats halved from the previous election to two to four.

The Japanese Communist Party might secure two to four seats, the same level as in the previous election, in which it won three. The Conservative Party of Japan may win several seats. As for the Social Democratic Party, the focus is on whether it can defend its one seat.

Among political groups, the Path to Rebirth has a chance of winning a seat.