As the four candidates in the Sept. 20 Liberal Democratic Party presidential election delivered policy speeches Tuesday, Shizuka Kamei stepped up his criticism of Mikio Aoki.

Aoki is a party heavyweight who has decided to support Prime Minister Junichiro Koizumi in the election even though he belongs to a faction hostile to Koizumi.

"It's a serious problem that a senior leader in the party would do such a thing," Kamei, a candidate in the election, said in a policy speech before LDP Diet members and supporters.