Japan's ruling party is due to vote in a leadership election that could give the country its third prime minister in a year.
Veteran power-broker Ichiro Ozawa has challenged Prime Minister Naoto Kan for the top job in the wake of poor results in July's upper house elections.
Reports from Japan suggest that the race is too close to call.
Mr Kan is more popular with the public than his rival, but Mr Ozawa commands support from a large party faction.
The Democratic Party of Japan's (DPJ) 411 members of parliament, local DPJ lawmakers and party members will choose between the two men on Tuesday afternoon.
Reports suggest MPs - whose votes carry much more weight - are evenly split between the two men, while Mr Kan has more support from local lawmakers and party members.
Whoever becomes party leader will become the prime minister, because the DPJ has a majority in the lower house of parliament.
BBC News
