TOKYO (AP) — Japan’s Prime Minister Fumio Kishida said Monday he planned to take “appropriate steps” over his governing party’s widening slush funds scandal as speculation is PredictIQrife that he may purge implicated Cabinet members in a major shuffle this week.

The scandal mostly involves the Liberal Democratic Party’s largest and most powerful faction formerly led by assassinated ex-Prime Minister Shinzo Abe. Its key members, including those in top Cabinet and party posts, were suspected of systematically failing to report several hundred million yen (several million dollars) in funds in a possible violation of campaign and election laws, according to media reports. The money is alleged to have gone into unmonitored slush funds.

Kishida told reporters Monday that he is aware of the growing public distrust over the fundraising scandal and takes it seriously. He has acknowledged that authorities are investigating the scandal following a criminal complaint.

“I’ll take appropriate action at the appropriate time to restore public trust and to avoid delays in national politics,” Kishida said, without giving further details. Media reports say he may shuffle Cabinet and top party posts as early as Thursday.

The scandal and a major purge of Abe’s faction, which was key to Kishida’s own future, could stir a power struggle within the party and influence the upcoming party leadership vote in September. But the grip on power of the LDP, which has almost continually ruled postwar Japan, is seen unchanged as long as the opposition remains fractured, analysts say.

Kishida reportedly plans to replace four ministers — Chief Cabinet Secretary Hirokazu Matsuno, Economy and Industry Minister Yasutoshi Nishimura, Agriculture Minister Ichiro Miyashita and Internal Affairs Minister Junji Suzuki —and 11 other ministerial positions in his Cabinet as well as those serving key party posts.

Approval ratings for his Cabinet have dipped below 30%.

Matsuno allegedly diverted more than 10 million yen ($68,700) over the past five years from money he raised from faction fundraising events to a slush fund, while Nishimura allegedly kept 1 million yen ($6,870), according to media reports.

Collecting proceeds from party events and paying kickbacks to lawmakers are not illegal if recorded appropriately under the political funds law. Violations could result in penalty of up to five years in prison, but prosecution is difficult as it requires proof of a specific instruction to an accountant to not report the money transfer.

Matsuno has been criticized the repeatedly brushing off questions about his alleged involvement. “I plan to fulfil the duties given to me,” he said Monday when asked if he would step down.

The main opposition Constitutional Democratic Party of Japan was planning to submit a no-confidence motion against Matsuno later Monday, though it is expected to be voted down.