TOKYO –  Japan’s next Prime Minister will be either Agriculture Minister Shinjiro Koizumi or former economic security minister Sanae Takaichi, who are facing off in a run-off vote in the race to succeed Mr Shigeru Ishiba.

The final winner of the ruling Liberal Democratic Party (LDP) election on Oct 4 will be known at around 3.20pm Japan time (2.20pm Singapore time).

Either candidate would be historic for Japanese politics. The telegenic Mr Koizumi, 44, a political scion whose father Junichiro had been PM from 2001 to 2006, will be the youngest postwar PM. Ms Takaichi, 64, a conservative protege of the late PM Shinzo Abe, would become the country’s first female leader.

Both had drawn controversy during the hustings.

Ms Takaichi made borderline xenophobic claims about foreigner crime and abuse in a nationalist campaign speech, while Mr Koizumi’s campaign was found to have engaged in “stealth marketing” on social media platforms to boost his profile and deride his competitors.

The other candidates in what had been a five-horse race were Chief Cabinet Secretary Yoshimasa Hayashi, 64; former economic security minister Takayuki Kobayashi, 50; and former foreign minister Toshimitsu Motegi, 69.

The contest on Oct 4 was triggered by

Mr Ishiba’s announcement on Sept 7 that he would step aside

to prevent a party split. Mr Ishiba, who took office on Oct 1, 2024, had been facing a coup from rivals baying for blood after electoral drubbings left the ruling coalition without a majority in both chambers of Parliament.

The winner will see out the remaining two years of Mr Ishiba’s three-year tenure as LDP president, with the next party leadership race to be held in 2027.

The first round involved 590 votes, with the party’s 295 elected lawmake...