Japan's ruling LDP to pick new leader on October 4, Takaichi and Koizumi seen as frontrunners

TOKYO (Reuters) - Japan's ruling Liberal Democratic Party will elect a new leader on October 4 to replace outgoing Prime Minister Shigeru Ishiba, senior party lawmakers said on Tuesday, after a formal contest rather than a simplified voting procedure.

One senior LDP lawmaker said the full-scale selection procedure may favour Sanae Takaichi, a veteran fiscal dove and right-winger who local media say has decided to run, as well as Farm Minister Shinjiro Koizumi, the son of former premier Junichiro Koizumi. They are among a field likely to include at least five candidates, although neither has announced their candidacy yet.

In the first round of the contest each LDP lawmaker in the Diet casts one vote, and rank-and-file party members' choices are divided proportionally into an equal number of votes to those of the Diet members, so that the result reflects the wider views of party members.

Takaichi and Koizumi, who gained prominence as Ishiba's farm minister tasked with curbing soaring rice prices, have each run before and placed second and third respectively in the leadership contest in September 2024 that was eventually won by Ishiba.

Other potential candidates include former foreign minister Toshimitsu Motegi, who announced his bid on Monday, as well as Chief Cabinet Secretary Yoshimasa Hayashi, according to a source close to the government's top spokesperson.

Ishiba announced his resignation on Sunday, in the wake of elections that saw his ruling coalition lose its majority in both houses of parliament amid voter anger over the rising cost of living.

(Reporting by Kaori Kaneko and Yoshifumi Takemoto; Editing by Himani Sarkar and Hugh Lawson)