(Reuters) - Japanese Prime Minister Naoto Kan risks losing his job after ruling party rebels said they would back a no-confidence motion in parliament. If it passes, Kan, Japan's fifth premier in as many years, will have to resign or call a snap election.
The following are possible successors. All are ruling Democratic Party of Japan (DPJ) MPs except Sadakazu Tanigaki, who heads the main opposition Liberal Democratic Party (LDP):
Maehara, 49, is a defense policy expert who favors tight ties with the United States. He has voiced concern about China's military buildup but wants good relations with Beijing.
"I want to make this year a year to push further for forward-looking Japan-China ties," he told Reuters in a January interview. "At the same time, it is important to say things firmly on issues of our concern."
Maehara quit as foreign minister in March, taking responsibility for accepting donations from a foreign national.
Although known more for his views on diplomacy and defense than the economy, Maehara has advocated streamlining public works projects. He studied at the Matsushita Institute of Government and Management, a school for political leaders. Many of its graduates embrace free markets and conservative security policies.
He briefly led the Democrats' in 2006. His hobbies include taking pictures of steam trains.
A former internal affairs minister, Haraguchi, 51, is close to party powerbroker Ichiro Ozawa. He intends to back the no-confidence motion.
In a magazine article earlier this year, he threatened to create a "DPJ-A" group that would put priority on economic growth and stick to costly campaign promises.
He entered politics as a local assembly member for the then-ruling Liberal Democratic Party (LDP), which he left after Ozawa quit the party in 1993.
Haraguchi, who studied at the same political leadership school as Maehara, tweets and blogs and is a frequent guest on TV talk shows, but lacks clout within the DPJ.
Noda, 54, currently finance minister, has backed Kan's push for fiscal and tax reforms, including a future sales tax hike.
Noda also attended the Matsushita Institute of Government and Management. Unlike many politicians, Noda is not from a privileged background and is the son of a member of the military. He started in regional politics in 1987 and joined the DPJ about a decade ago, earning a reputation as an orator.
He drew fire from the opposition early in March after he said he had received a donation from a firm run by a man indicted for tax evasion. He said he would give the money back. A fan of combat sports, he is a keen judo practitioner.
Tarutoko, 51, ran against Kan in a party leadership race last June but lost by a wide margin. Tarutoko later backed Ozawa in a leadership vote in September, which Kan won again.
Tarutoko, who served as the party's chief of parliamentary affairs, has said he opposes raising the sales tax to help pay for reconstruction after the March tsunami.
Last month, he proposed a grand coalition with the LDP for a limited period to spearhead the reconstruction.
Gemba, 47, is the party's policy chief and National Strategy Minister. He has led efforts to review the party's 2009 campaign pledges, which critics say were too ambitious. An advocate of deregulation, he has supported a sales tax rise.
His electoral district is in Fukushima prefecture, where the tsunami-crippled nuclear power plant has been leaking radiation.
Sengoku, 65, was Kan's No.2 cabinet minister until January, when he was removed after an upper house censure motion over his handling of a territorial dispute with China.
The former lawyer has said that he feels a "sense of crisis" about Japan's public finances. Although a former member of the now defunct Socialist Party, he supports free-market policies. He now serves as deputy chief cabinet secretary and said recently some sort of broad coalition would be needed to overcome the parliamentary logjam.
Edano, 47, replaced Sengoku as chief cabinet secretary and for weeks was the public face of Japan during the crisis sparked by the March 11 disaster, impressing the public with his calm.
Edano is an unlikely candidate given his relative youth and prominent role in Kan's cabinet, though a recent poll showed voters would like him to play a greater political role.
Watanabe, 79, a party elder who joint the lower house of parliament more than 40 years ago has served as health minister and trade minister. He suggested in February that Kan's resignation could win opposition support for bills to enact a workable budget. Like Gemba, he represents Fukushima.
Kano, 69, serves as agriculture minister.
He has been reserved about Japan's possible participation in a U.S.-led free trade initiative, the Transpacific Partnership, saying reconstruction efforts should have priority.
Kano has spearheaded aid to northern Japan's farming and fishing industries after the March disaster.
Tanikagi, 66, leads the main opposition LDP, which enjoyed more than 50 years of almost unbroken rule before losing to the Democrats in a 2009 election. Tanigaki rejected Kan's offer in March to join the cabinet as deputy premier for disaster relief.
Like Kan he sees the need to raise the sales tax, but argues the Democrats must also cut spending such as child allowance payouts.
Reporting by Kiyoshi Takenaka, Editing by Jonathan Thatcher