TOKYO – Toshimitsu Motegi on Thursday left his foreign minister post and became the ruling Liberal Democratic Party secretary general, vowing to press ahead with reforming the party and getting it ready for the House of Councillors election next year.

The appointment of Motegi came after his predecessor Akira Amari resigned following his defeat in a single-seat district in Sunday’s House of Representatives election, an unprecedented humiliation for the LDP while in power, even though he was elected through the proportional representation ballot. Amari had been in the post for only a month.

“An upper house election is slated for next summer, and I would like to steadily make preparations for a victory,” Motegi said in his first press conference after the appointment, while noting the need to analyze why LDP candidates in some areas struggled in the latest election.

He said Amari has, during his short tenure as secretary general, helped the LDP win 261 seats, a comfortable majority in the powerful lower chamber.

In addition to preparations for the election, Motegi said Prime Minister Fumio Kishida has instructed him to work on helping lead the country out of the coronavirus pandemic as a priority and carry out reforms in the party.

Kishida said he will double as foreign minister until he picks the new foreign minister and convenes a special session of parliament next week, during which he is expected to be re-elected as premier.

Among candidates to succeed Motegi as foreign minister is former education minister Yoshimasa Hayashi, sources close to the matter have said.

Under the Constitution, the Cabinet must resign en masse when the first session of the Diet is convened following a general election. In a special session expected to be held on Wednesday, the Diet is set to choose Kishida as the prime minister, and he will then relaunch the Cabinet.

Marking one month since he became prime minister, Kishida told reporters on Thursday, “Since I have gained the people’s mandate through the general election, I now plan to speedily implement policies” on key issues such as the coronavirus pandemic as well as economic and diplomatic challenges.

Motegi, former policy chief of the LDP, heads one of the seven major intraparty factions and backed Kishida in the party leadership race in September. He is also known for having close ties with former prime ministers Shinzo Abe and Taro Aso.

In Sunday’s election of the 465-member lower chamber, Motegi easily secured his seat in his constituency in Tochigi Prefecture, while Amari lost his district in Kanagawa Prefecture before managing to secure a seat through proportional representation.

In 2016, Amari resigned as economic and fiscal policy minister amid graft allegations. Opposition lawmakers have continued to target him with criticism for failing to provide a sufficient explanation over his role in the scandal.