TOKYO - Japan's Liberal Democratic Party (LDP) has decided to hold its upcoming leadership election in a full-scale format, including votes from both lawmakers and rank-and-file party members, to select a successor to Prime Minister Shigeru Ishiba.

At a meeting on Tuesday, party executives agreed that the election will be officially announced on Sept 22, with lawmakers casting their ballots on Oct 4.

In the full-scale format, the contest will be decided by 590 votes in total, 295 from LDP lawmakers and 295 from party members. The campaign period will last more than 12 days.

LDP Secretary-General Hiroshi Moriyama emphasized that a full-scale election is the most desirable way to elect a new leader, describing it as an opportunity for the party to reset and move forward as a national political force.

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Under the election rules, a winner must obtain more than half of the votes in order to be elected as the new party chief, and 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 LDP lawmakers vote a second time and the 47 prefectural chapters get one vote each.

With Ishiba stepping down, the LDP is bracing for a heated leadership contest as major contenders signal their intention to run.

Former Foreign Minister Toshimitsu Motegi on Monday announced his intention to run, pledging to devote his full political experience to the party and government.

Chief Cabinet Secretary Yoshimasa Hayashi and former Economic Security Minister Sanae Takaichi have also decided to run, local media reported.