Prime Minister Yoshihiko Noda looked to be struggling on Friday to win backing from his own party for Japan to join talks on a U.S.-led free trade pact that could transform the Japanese economy.

Noda is due to fly on Saturday to Hawaii for a meeting of Asia-Pacific leaders where he is due to tell other members in the proposed trade fact whether Japan will join.

He had been expected to make an announcement on Thursday but that has been delayed by the failure of the government and ruling party officials to reach a conclusion.

I am aware that many are wary of joining the negotiations. I would like to keep this in mind when finalizing my decision. he told lawmakers.

As I have said before, I would like to go through with a thorough discussion on the subject and come up with a conclusion promptly.

Membership of the Transpacific Partnership (TPP) would wrench open Japan's closeted agriculture sector to competition, give its major exporters better tariff deals overseas and challenge a political system over which the farm lobby has long held powerful influence.

For Noda, who became Japan's sixth premier in five years only two months ago, the decision on trade talks is his first big test in the face of deep divisions in his ruling party and an opposition able to block laws.

Noda has highlighted economic benefits of tapping into dynamic markets of the Pacific Rim region, which made many commentators take for granted that he would push for joining the talks despite opposition within his party and the general public.

But the delay in a decision raised questions about Noda's commitment.

He has not really led the intra-party debate on the issue, and that is clear in the eyes of the public, said Tetsuro Kato, political science professor at Waseda University.

I think it is certain that his support rate will take a tumble, with high expectations people had for his leadership at the time of his taking office dwindling.

When he took power two months ago hopes were high that the uncharismatic former finance minister could succeed where his short-lived predecessors failed: get things done by working quietly behind the scenes and forging necessary consensus.

Those hopes were reflected in Noda's initial popularity ratings well above 50 percent. But in two polls published this week his ratings for the first time sunk below 50 percent, in part due to public discontent with the way he has handled the debate about the trade pact.

The agreement that would in principle eliminate all tariffs and other trade barriers is now discussed by nine nations -- Australia, Brunei, Chile, Malaysia, New Zealand, Peru, Singapore, the United States and Vietnam.

(Additional reporting by Shinichi Saoshiro, Editing by Jonathan Thatcher)