Campaigning for the Sept. 20 Liberal Democratic Party presidential election officially kicked off Monday.

Three lawmakers who advocate higher government spending are challenging the reform agenda of the incumbent party chief, Prime Minister Junichiro Koizumi.

In addition to Koizumi, former transport minister Takao Fujii, former LDP policy chief Shizuka Kamei and former Foreign Minister Masahiko Komura registered their candidacies at the LDP's headquarters in Tokyo.