Naoto Kan, leader of the largest opposition Democratic Party of Japan, will become head of the newly expanded version, leaders of the four parties involved decided at a meeting March 31.

The new party will be formed in about two weeks under the DPJ banner through the amalgamation of the current DPJ, Minseito (Good Governance Party), Shinto Yuai (Amity Party) and the Democratic Reform Party.

Tsutomu Hata, Minseito's leader and a former prime minister, will assume the No. 2 post of secretary general. Kansei Nakano, Shinto Yuai's head, and DRP leader Teiko Sasano will serve as vice chiefs of the new party.

Koichi Kato, secretary general of the ruling Liberal Democratic Party, said he doubts Kan will be able to effectively exercise leadership and steer a party that consists of different parties, even though various opinion polls rank him as the nation's most popular politician.

Kan, 51, who is now serving his sixth term as a House of Representatives member, emerged as the politician most favored to become prime minister in recent opinion polls. Kan is popular chiefly because he took a leading role in uncovering the role of Health and Welfare Ministry officials in a scandal over HIV-tainted blood products when he headed the ministry in 1996. At the time, he belonged to New Party Sakigake, a parliamentary partner of the ruling Liberal Democratic Party.

Kan was first elected to the Lower House from a Tokyo constituency in 1980 after two failed attempts. He then belonged to the defunct United Social Democratic Party.