Campaigning has begun in Japan for the leadership of the ruling Liberal Democratic Party.
By Jonathan Head
BBC correspondent in Tokyo
Three senior party members representing different factions are challenging Prime Minister Junichiro Koizumi.
The winning candidate automatically becomes prime minister.
Mr Koizumi (centre) has disappointed on the economy
Mr Koizumi, who won the position two-and-a-half years ago with promises of far-reaching reform, has been criticised for his failure to revive the Japanese economy.
However, he retains more popular support than any other LDP candidate.
Mr Koizumi's easy-going charisma has been on frequent display in recent weeks, from opening the pitching at a school baseball game, to visiting many of the country's hard-pressed industries.
He needs to make the most of his popularity with the people, because many in his own party would like to see him unseated.
Shizuka Kamei, 66: former LDP policy chief; favours revising pacifist constitution and more public spending
Masahiko Komura, 61: former foreign minister; wants less austere fiscal stance
Takao Fujii, 60: former transport minister; wants more public spending, but with better focus
Conservatives in the LDP are unhappy over his insistence on his own choice of ministers, not theirs, and his commitment to reforming Japan's business and political culture, even though he has failed to implement many of his bolder promises of change.
His opponents in the party argue that Mr Koizumi's new, independent style of leadership has not delivered any real improvements to the depressed Japanese economy.
As the prime minister is more popular with the rank-and-file of the party, he needs their support to win an overall majority in the first round of voting.
If he does not, he faces a run-off election against a single candidate in which only the members of parliament are allowed to vote.
However Mr Koizumi has two trump cards up his sleeve - the economy is now beginning to show signs of a real recovery, and he remains the only LDP candidate sufficiently popular with the public to ensure victory for the party at the next general election.