Who could succeed Shinzo Abe as Japan's prime minister?

Contenders in the Liberal Democratic Party include current and former ministers

Japan's former defence minister Shigeru Ishiba is seen as seen as a strong orator with significant political experience. AFP

Japanese Finance Minister Taro Aso became prime minister in 2008 but stepped down after the Liberal Democratic Party suffered a historic defeat the following year. AFP

Defence Minister Taro Kono formerly served as Japan's foreign minister and is a passionate opponent of nuclear power. AFP

Fumio Kishida, also a former foreign minister, currently serves as policy chief in the Liberal Democratic Party. AFP

Japan's Cabinet Secretary Yoshihide Suga is a self-made politician and trusted adviser to Prime Minister Shinzo Abe. AFP / JJiji Press

Japanese Prime Minister Shinzo Abe's decision to resign over health problems has turned attention to who might succeed the country's longest-ruling premier, with no consensus yet clear on a candidate.

Here are some of the potential contenders:

Taro Aso, gaffe-prone finance minister

Taro Aso is a Liberal Democratic Party old-timer and close Abe ally who serves as finance minister and deputy prime minister

Mr Aso, 79, was prime minister from 2008-09 and has held his current posts since 2012.

He stepped down as premier after the LDP was booted from office in a historic defeat in 2009, and has long been rumoured to nurse hopes of another chance at the top office.

His long political career has been punctuated by repeated gaffes, including comments that the elderly should "hurry up and die" instead of costing the government money, and that Tokyo could learn from Nazi Germany when it comes to constitutional reform.

But he has weathered the multiple furores over his comments, and leads a major faction in the LDP.

He backed a massive stimulus programme in the face of the 2008 global financial crisis, but later shifted to stressing the importance of reducing the country's snowballing debt.

Shigeru Ishiba, popular former defence minister

Former defence minister Shigeru Ishiba is considered a military geek but is also a self-confessed fan of 1970s pop music.

The 63-year-old former banker is the scion of a political family and seen as a strong orator with significant experience – he entered parliament at just 29.

Like Mr Abe, Mr Ishiba is a defence hawk who wants to strengthen the role of the country's Self-Defence Forces in the pacifist constitution, and he has even mused about whether Japan should reconsider its policy forbidding nuclear weapons on its soil.

He has served in several cabinet posts and is a popular choice to succeed Mr Abe among the public.

Mr Ishiba is less favoured by his fellow ruling party lawmakers, partly because he once left the LDP.

He was the sole challenger to Mr Abe in the party's 2018 leadership contest and was heavily defeated.

Yoshihide Suga, power player and adviser

Yoshihide Suga, 71, rose to national prominence as a trusted Abe adviser and was a key proponent of his bid for the premiership after a disastrous first term.

After Mr Abe returned to power in 2012, he appointed Mr Suga chief cabinet secretary, a powerful position that co-ordinates the efforts of government ministries and the ruling party.

He is also often the face of the government, delivering regular press briefings and famously revealed the name of the new imperial era declared with the ascension of Emperor Naruhito in 2019 – the Reiwa era.

He is a rare self-made lawmaker in a ruling party filled with hereditary politicians and former technocrats, and is the eldest son of a strawberry farmer.

Mr Suga moved to Tokyo after high school and worked odd jobs to put himself through night college.

He was first elected in 1987, as a municipal assembly member in Yokohama, and won a lower house seat in 1996.

Fumio Kishida, favoured successor

Former foreign minister Fumio Kishida currently serves as the ruling party's policy chief and is often described as Mr Abe's preferred successor, but his soft-spoken, low-key presence and alleged lack of charisma are seen as possible obstacles.

Elected from Hiroshima, Mr Kishida worked to invite then-US president Barack Obama for a historic visit to the city that was devastated by the world's first war-time atomic bomb explosion.

He has been credited with helping cement a deal between Japan and South Korea in 2015 that was meant to end the long-running dispute between the countries over the use of sex slaves during Japan's occupation.

Taro Kono, colourful Twitter user

Defence Minister Taro Kono was once considered an ambitious and independent-minded political reformer, but the 57-year-old has toned down his rhetoric in recent years as a key member of Mr Abe's cabinet.

After a stint as a government reform minister, the Georgetown-educated politician served as foreign minister between 2017-2019 before becoming defence minister.

He travelled extensively as Japan's top diplomat, but also oversaw the deterioration of ties with South Korea over unresolved wartime disputes.

In recent years, he has largely avoided discussing his passionate opposition to nuclear power, given the government's official support, and despite his independent image he is seen as close to both Mr Aso and Mr Suga.

Often contrasted with his father, political dove Yohei Kono, he has also set himself apart with his online presence, maintaining personal Twitter accounts in Japanese and English.