Japanese Prime Minister Fumio Kishida on Thursday indicated the possibility of his ruling Liberal Democratic Party questioning former premier Yoshiro Mori about a political funds scandal that came to light late last year.

Mori "could be included" as a target of the LDP's investigation as "he is needed to clarify political responsibility," Kishida said at a parliamentary session, while declining to comment on whether the former leader was involved in the scandal.

The ruling party has come under intense scrutiny as some of its groups, such as the biggest faction formerly led by the late Prime Minister Shinzo Abe, neglected for years to report portions of income from fundraising parties, creating slush funds in the process.

Japanese Prime Minister Fumio Kishida speaks at a House of Councillors budget committee session in Tokyo on March 28, 2024. (Kyodo)

Mori, who headed the faction from December 1998 to April 2000 and from May 2001 to October 2006, is suspected of having crafted the scheme, although senior members of the group have claimed that they are unaware of when the slush fund practice began.

With the LDP suggesting the custom might have lasted for over 20 years, opposition parties have demanded that Mori, who served as prime minister for around one year from April 2000, be summoned to parliament as a sworn witness.

The senior lawmakers of the largest faction within the LDP, which has been in power for most of the period since 1955, have also said Abe decided to stop the practice of paying money back to its members at a meeting involving its executives in April 2022.

But they added the scheme was later reinstated following a gathering in August 2022, one month after Abe was fatally shot during an election campaign speech.

Abe's assassination and the death in November 2023 of former House of Representatives speaker Hiroyuki Hosoda, who led the faction for about seven years from 2014, has made it difficult for the LDP to probe how and when the group launched the slush funds practice.

The funds scandal has eroded public trust in politics, leading to a sharp decline in approval ratings for Kishida's Cabinet. The ratings have plummeted to their lowest levels since the Cabinet's launch in October 2021, falling well below 30 percent, a threshold widely recognized as the "danger level" for a government.

Three by-elections to fill vacancies in the lower house are scheduled for April 28. The LDP's support rate has also fallen to its lowest level since December 2012, when it scored a landslide victory in the general election and returned to power.

Depending on the results of the by-elections, LDP lawmakers could seek to oust Kishida as leader before the next general election amid speculation he will dissolve the lower house ahead of the party's presidential race around September, some pundits said.

At a press conference later Thursday, Kishida said that the upcoming by-elections will take place "against a backdrop of strong backlash" against the LDP, adding that the party will strive to restore public trust in politics through the campaigns.

When asked about the possibility of dissolving the lower house before the by-elections, Kishida said, "I will devote myself to resolving challenges that cannot be postponed, and I do not think about anything else."

Regarding the by-elections, up for grabs are seats in the Tokyo No. 15 district, the Shimane No. 1 district and the Nagasaki No. 3 district, all of which were held by LDP lawmakers before they became vacant.

The LDP has yet to decide on a candidate for Tokyo and Nagasaki. In Shimane, the race is set to be a one-on-one battle with the main opposition, the Constitutional Democratic Party of Japan.

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