Tokyo Gov. Shintaro Ishihara is likely to form a new political party should Prime Minister Junichiro Koizumi lose in the Sept. 20 Liberal Democratic Party presidential election, Ishihara's son said Sunday.

"I think there will be a new Ishihara party," Nobuteru Ishihara, state minister in charge of administrative reform, said on a TV Asahi program.

"If there is anything that blocks Prime Minister Koizumi's track, it would be the end of the LDP" for having lost the public's support, Ishihara said, backing the prime minister.

Koizumi will face at least three challengers in the party presidential election. Former Transport Minister Takao Fujii, former Foreign Minister Masahiko Komura and former party policy affairs chief Shizuka Kamei have thrown their hats into the ring.

It has been widely speculated that the outspoken yet popular Tokyo governor and former Diet member would attempt to return to national politics by launching a new political party.

The governor is known for his confrontational style with the national government. Despite his controversial policies and nationalistic and discriminatory comments about non-Japanese, he was re-elected to a second term in April with overwhelming popularity.

"Accomplishments have been made in two years' time," Ishihara said, referring to Koizumi's structural reform promises.

He said the prime minister's reforms of public corporations are efforts to downsize the fiscal investment and loan program, known as the second budget, to downsize the government.