TOKYO (Kyodo) -- The ruling Liberal Democratic Party on Tuesday formally decided to hold its leadership election on Sept. 20, in what is likely to be a two-way battle between Prime Minister Shinzo Abe and former Defense Minister Shigeru Ishiba.
The LDP election effectively determines who will be prime minister. If Abe wins, he would be ensured a third term and be on track to become Japan's longest-serving leader.
The Abe-led LDP won a landslide victory in the House of Representatives election in October last year. The next lower house election will be held in 2021 unless the body is dissolved.
With the official LDP leadership campaign beginning on Sept. 7, it is expected to effectively be the first such election in six years, as Abe was re-elected unopposed for his second consecutive three-year term in 2015.
Although he has yet to officially throw his hat into the ring, the incumbent party president is widely viewed as leading the race since five of seven intraparty factions have expressed their support for him.
Abe, whose tenure expires on Sep. 30, is likely to declare his candidacy next week, according to party sources.
Abe told reporters he wants to "boost everyday" his drive and physical strength in the run-up to the election. He made the remark while playing golf during his summer retreat in the village of Narusawa, Yamanashi Prefecture.
Ishiba, who has assumed key posts such as minister in charge of revitalizing local economies and LDP secretary general under Abe's reign, is seeking to broaden his support base among rank-and-file party members, who will also cast their ballots in the race.
Despite the odds being against him, Ishiba indicated on a television program Tuesday that if he or any other candidate did not run, this would undermine democracy in the country.
In the first round of voting, the contenders will aim to secure a majority among 810 votes -- 405 by lawmakers and the same number by rank-and-file members. If none of them wins a majority in that stage, a runoff will be held in which ballots by Diet members weigh more.
In a party meeting on Tuesday, the LDP confirmed that it will lower the minimum voting age for the leadership contest among its members to 18 from 20 in line with the voting age for public elections.
One of the main issues will likely be revisions to the Constitution, in particular its war-renouncing Article 9. While the two likely contenders share the intention to amend Japan's supreme law, they are different in their approach to dealing with Article 9.
Abe has called for adding an explicit reference to the Self-Defense Forces to ensure there is no way for them to be deemed "unconstitutional."
Earlier this month, Abe said his party should submit constitutional revision proposals to the extraordinary Diet session expected to be convened in the fall.
Ishiba, known as a security hawk, has proposed drastically rewriting Article 9, in a way that implies removing the current postwar constraints imposed on the SDF activities.
But speaking in a press conference on Friday, he insisted amendments to Article 9 should not be rushed, citing a lack of public understanding of the issue.
Ishiba did however stress the urgency of revising the Constitution on points such as giving the prime minister extraordinary power in case of emergencies including natural disasters.