Senior LDP member Taku Yamasaki said Wednesday he has not decided what stance he will take if a no-confidence motion is introduced against Prime Minister Yoshiro Mori.

"I have not reached any conclusion. I need to carefully evaluate the timing of the motion and reach a consensus with my colleagues," the former policy chief of the Liberal Democratic Party said, referring to the faction of about 25 members he leads.

The 64-year-old House of Representatives lawmaker on Monday became the first to voice an intention to try to succeed the unpopular prime minister.

"If a no-confidence motion is rejected, we have few measures to force the prime minister -- when he is determined to remain in power -- to step down," Yamasaki told a gathering at the Foreign Correspondents Club of Japan. "It would be possible for him to survive until the House of Councilors election slated in July."

Despite growing pressure on Mori to step down, even from within the ruling bloc, Yamasaki is so far the only LDP lawmaker to suggest he might run for the party presidency should Mori vacate it.

Yamasaki, however, said he is torn between his desire to seek power and the need to lead his faction.

"It is true we faced strong criticism after the 'Kato feud'," he said, referring to an aborted rebellion in November staged by Koichi Kato, his political ally and a former LDP secretary general once considered a likely candidate for prime minister.

Kato told members of his faction to support a no-confidence motion the opposition planned to submit to the Diet.

At the last moment, however, Kato changed his mind and skipped the voting, allowing the ruling bloc to defeat the anti-Mori motion.

Yamasaki has since put his faction members in the awkward position of being ostracized by the party's mainstream.