By Linda Sieg
TOKYO, Aug 24 (Reuters) - Japan's longest-serving prime minister, Shinzo Abe, visited a Tokyo hospital on Monday, as concerns grew over his ability to continue in his post, because of health issues and fatigue from handling the coronavirus crisis.
If Abe is incapacitated, Deputy Prime Minister Taro Aso, who doubles as finance minister, would take over temporarily. If Abe resigned, he would stay on until formally replaced, which would require the ruling Liberal Democratic Party (LDP) to elect a new leader, who would then be formally elected in parliament.
Here are details of some likely contenders to take the helm of the world's third-largest economy.
TARO ASO
Finance minister Aso, 79, who also doubles as deputy prime minister, has been a core member of Abe's administration. Without a clear consensus on who should succeed Abe, LDP lawmakers could elect Aso as a temporary leader if Abe resigns.
In 2008, Aso was elected LDP leader and hence, premier, in hopes that he could revive the long-dominant party's fortunes. Instead, the LDP was ousted in a historic election defeat in 2009, languishing in the opposition for the next three years.
The grandson of a former premier, Aso mixes policy experience with a fondness for manga comics and a tendency towards gaffes.
SHIGERU ISHIBA
A hawkish former defence minister and rare LDP critic of Abe, Ishiba, 63, regularly tops surveys of lawmakers whom voters want to see as the next premier, but is less popular with the party's lawmakers.
The soft-spoken security maven has also held portfolios for agriculture and reviving local economies.
He defeated Abe in the first round of a party presidential election in 2012, thanks to strong grassroots support, but lost in the second round when only MPs could vote. Then, in a 2018 party leadership poll, Ishiba lost heavily to Abe.
He has criticised the Bank of Japan's ultra-low interest rates for hurting regional banks and called for higher public works spending to remedy growing inequality.
FUMIO KISHIDA
Kishida, 63, served as foreign minister under Abe from 2012 to 2017, but diplomacy remained mainly in the prime minister's grip.
The low-key lawmaker from Hiroshima has been widely seen as Abe's preferred successor but ranks low in voter surveys.
Kishida hails from one of the party's more dovish factions and is seen as less keen on revising the post-war constitution's pacifist Article 9 than Abe, for whom it is a cherished goal.
The BOJ's hyper-easy monetary policy "cannot go on forever," Kishida has said.