TOKYO - Japan's ruling Liberal Democratic Party (LDP) on Thursday officially began its leadership race as the two-week campaign started, with a record nine candidates competing to become the new party chief and the country's next prime minister.

The contest for the position of LDP president, which carries a three-year term until 2027, kicked off amid declining trust for the party in the wake of its slush fund scandal, with party reform being a key issue in the upcoming election.

The candidacies were filed at LDP headquarters on Thursday morning, with the official start of the election announced by party lawmaker Ichiro Aisawa in his capacity as chairman of the LDP's election administration committee.

As both houses of parliament are controlled by the LDP and its coalition partner, the Komeito party, the winner is certain to become prime minister early next month when the Diet, Japan's parliament, reconvenes.

Upon current Prime Minister Fumio Kishida's decision last month to not seek reelection as the LDP president, the election has become the most crowded race in the party's history and one of the most unpredictable, according to local media reports.

As the 15-day campaign began on Thursday, the nine presidential candidates would set out on a nationwide campaign, engaging in debates, delivering stump speeches, and lobbying local LDP chapters.

Voting and ballot counting are slated to take place on Sept 27, when the candidates will compete for a total of 734 votes, of which 367 are cast by LDP lawmakers and 367 by general party members.

A winner must obtain more than half of the votes in order to be elected as the new party chief, however, if no one wins a majority in the first round, a run-off vote between the top two candidates will be held on the same day, when the 47 prefectural chapters get one vote each and the 367 lawmakers vote a second time.

Among the veteran candidates and public favorites is former Defense Minister Shigeru Ishiba, 67, making his fifth and final bid to become LDP chief over his 38-year political career.

Another hopeful vying for the LDP presidency is 43-year-old Shinjiro Koizumi, a former environment minister and son of former Prime Minister Junichiro Koizumi.

Two female contenders are Economic Security Minister Sanae Takaichi, 63, and Foreign Minister Yoko Kamikawa, 71.

Other candidates include former Economic Security Minister Takayuki Kobayashi, 49; Digital Minister Taro Kono, 61; Chief Cabinet Secretary Yoshimasa Hayashi, 63; LDP Secretary-General Toshimitsu Motegi, 68; and former Chief Cabinet Secretary Katsunobu Kato, 68.

According to an opinion poll conducted by the Japanese newspaper Nihon Keizai Shimbun in late August, Koizumi has emerged as the most popular candidate with 23 percent support. Ishiba was second at 18 percent and Takaichi third with 11 percent.