Prime Minister and Liberal Democratic Party President Junichiro Koizumi stressed Monday he will step down immediately if the ruling coalition fails to win a majority in the 480-seat House of Representatives in the Sept. 11 election.

"I will step down even if (the result) is only one seat short" of 241, Koizumi said during a televised debate with leaders of the six major parties hosted by the Japan National Press Club in Tokyo.

The LDP usually increases its seat count after an election by bringing conservative lawmakers who successfully ran as independents into its fold. Koizumi's remarks, however, effectively ruled this out for the Sept. 11 race and shut the door on forming alliances with third parties afterward.