Former Defense Minister Shigeru Ishiba said Thursday he will declare his candidacy for the leadership of the ruling Liberal Democratic Party, in what is expected to be a two-horse race with Prime Minister Shinzo Abe.
"Tomorrow I want to state my ideas about the race to pick the (LDP) president," Ishiba told a meeting of his own faction. The party election will be held in September.
As the vote will effectively decide the next prime minister, the 61-year-old said he will seek support for his views on issues ranging from the revision of Japan's pacifist Constitution to security, diplomacy and party management.
The leadership contest is expected to be a battle only between Ishiba and Abe, who is widely favored to win a third term as LDP leader and thereby become Japan's longest-serving prime minister.
Another possible candidate, Internal Affairs and Communications Minister Seiko Noda, is struggling to secure the necessary support from 20 LDP lawmakers to throw her hat into the ring.
Abe, 63, has already secured the support of five of the seven LDP factions, which make up of around 260 of the 405 LDP lawmakers across both chambers of the Diet.
A relatively large faction led by Wataru Takeshita, who chairs the LDP's decision-making General Council, will be divided between support for Abe and Ishiba.
Ishiba will likely gain the backing of around 45 LDP lawmakers, including the 20 members who belong to his own faction and some of those who belong to the Takeshita faction.
A total of 73 LDP lawmakers do not belong to any intraparty group.
In the first round of voting, the contenders will seek to secure a majority from among the 405 votes by legislators and the same number by rank-and-file members. If none of them wins a majority in the initial stage, a runoff will be held in which ballots by Diet members weigh more.
Abe, who took office in December 2012, has had an unrivaled grip on power and was re-elected unopposed for a second term as LDP president in 2015. His current three-year term as president expires on Sept. 30.
Ishiba was defeated in the 2012 LDP leadership election in a runoff with Abe.