The abrupt departure of Japanese Prime Minister Shinzo Abe has triggered a race within the ruling Liberal Democratic Party for the top job, with no single contender having a clear road to the premiership.

Whoever succeeds Abe, the country's longest-serving prime minister, will have their work cut out as the coronavirus pandemic has plunged the world's third-largest economy into recession and forced the Tokyo Olympics to be postponed.

Combined photo taken in July 2019 shows (from L) Japanese Chief Cabinet Secretary Yoshihide Suga, Liberal Democratic Party policy chief Fumio Kishida and former LDP Secretary General Shigeru Ishiba. (Kyodo)

Frontrunners include LDP policy chief Fumio Kishida and former Defense Minister Shigeru Ishiba, both of whom indicated their desire to run shortly after Abe announced Friday his intent to step down in an at times emotional press conference. Meanwhile Chief Cabinet Secretary Yoshihide Suga, also seen as a top contender, has avoided openly voicing any ambitions he may be harboring.

Abe himself declined to name his preference for the next LDP leader and therefore prime minister, simply calling on his party to make its choice as soon as possible.

LDP leaders are chosen by election, with hopefuls first being required to gather 20 nominations from among the party's Diet members to run.

After at least 12 days of campaigning, the election is held and -- usually -- whoever gets the majority of the 788 votes up for grabs wins. Diet members hold 394 of the votes and rank-and-file members account for the other 394.

But ballots for the rank-and-file members have to be mailed across the country. This takes time, and in emergencies where a leader must be chosen quickly, like a pandemic, a scaled-down version of the election can be held with Diet members and three delegates from each of the 47 prefectural chapters participating for a total of 535 available votes.

According to a senior LDP lawmaker, Secretary General Toshihiro Nikai, to whom Abe has delegated authority to make a decision on the matter, plans to opt for the latter, with the election being eyed for Sept. 15.

An abbreviated election would almost certainly be a deathblow to Ishiba's chances at the premiership. Known as a strong debater and vocal Abe critic, the 63-year-old lost to Abe in the previous LDP leadership race in 2018 but has consistently topped the prime minister in recent public opinion polls asking who is most fit to run the country.

In that previous election, Abe edged out Ishiba in the number of votes from rank-and-file members but received 4.5 times as many from Diet members. Leading one of the smaller factions within the LDP with 19 lawmakers, Ishiba needs to win over lawmakers if he hopes to have a chance.

"Ishiba won't be able to overcome the party's resistance in the short time window," said Tobias Harris, a Japan expert at consulting firm Teneo Intelligence and author of a recently released biography of Abe, "The Iconoclast: Shinzo Abe and the New Japan."

Kishida, meanwhile, leads a midsize faction with 47 lawmakers, one of the more liberal groups within the LDP. The former foreign minister has long been considered the "heir" to Abe, patiently waiting his turn to become prime minister.

But Kishida, 63, has often struggled to find the limelight. Some, even within his inner circle, say he lacks charisma, which could become a liability for LDP lawmakers in a snap election or when the House of Representatives' current term ends in October 2021.

While Suga has long maintained he has no intention to pursue the top job, saying he has "never thought about it," he has become a powerful figure as one of Abe's closest aides since the prime minister's return to power in late 2012.

While Suga does not belong to a faction and therefore has fewer guaranteed votes, Harris said he has "clear strengths on the merits," having been a top decision maker for nearly eight years and providing continuity with the previous administration.

The 71-year-old received a popularity boost for his role in announcing the name of the new imperial era, Reiwa, though he has also been criticized for the government's push to promote domestic tourism despite coronavirus concerns, and his relationship with former Justice Minister Katsuyuki Kawai, who was arrested for alleged vote-buying along with his lawmaker wife Anri.

Other potential contenders include Foreign Minister Toshimitsu Motegi, 64, and Defense Minister Taro Kono, 57, though neither has announced plans to run yet. Both are U.S.-educated and fluent in English, which would be a valuable asset in raising Japan's profile on the global stage.

A key player in the election is Finance Minister Taro Aso. The longtime Abe ally who himself held the premiership from 2008 to 2009 said Friday he will not seek a second turn in power, saying he would throw the support of his 54-member faction behind whoever can best implement policies that align with his thinking.

That would likely be Kishida, Masahiro Iwasaki, a professor of political science at Nihon University, said, adding Aso will seek to continue to exert his influence over the new administration as "kingmaker."

LDP election strategy chief Hakubun Shimomura, a member of the party's largest faction with 97 lawmakers, has also said he will seek the top job, while former defense minister and Abe protege Tomomi Inada and former internal affairs minister Seiko Noda have said they are considering a run.

The winner of the upcoming election will serve out the rest of Abe's term through September 2021, at which point another vote will be held to determine the LDP leader for the following three years.

The next prime minister will inherit an economy that has been shattered by the coronavirus as consumers spend less time outside and tourism from overseas has virtually stopped altogether. Preparations for the delayed Tokyo Olympics and Paralympics need to be completed, though there is still no guarantee the Games can be held in summer 2021.

On the diplomatic front, there are a heap of outstanding issues including rocky relations with South Korea, a territorial dispute with Russia, securing the return of Japanese nationals abducted by North Korea in the 1970s and 1980s and the growing influence of China.

The incoming premier will also either deal with another four years of U.S. President Donald Trump, who has pushed for lower agriculture tariffs and a bigger contribution to the Japan-U.S. security alliance, or a new administration under Democratic nominee Joe Biden.

"The Shinzo-Donald relationship is over. (The new prime minister) will have to build a new relationship from the ground up while taking care not to be pushed around by America," Iwasaki said.

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