TOKYO, OCT. 27 -- When the Japanese parliament launched a special session two weeks ago to authorize the dispatch of troops to the Persian Gulf, Prime Minister Toshiki Kaifu stood at the front of the chamber like the proud helmsman of a mighty ocean liner. Today, he looks more like the captain of the Titanic.

The impassioned debate on legislation to create a "United Nations Peace Cooperation Corps" has been nothing less than a disaster for Kaifu. Since the parliament, or Diet, took up his bill, opposition party leaders as well as the general public have hardened their positions against it. And if Kaifu loses on the bill -- a plausible prospect -- there is a good chance he could lose his job as well.

The chief problem seems to be that the prime minister and his Liberal Democratic Party (despite the name, the LDP is the most conservative of Japan's major parties) got too far ahead of public opinion.

The national commitment here to the anti-military "peace constitution" imposed on Japan by the U.S. occupation in 1947 and the popular desire to maintain a strictly non-violent role in world affairs have turned out to be stronger and deeper than the politicians had expected. In opinion polls, on talk shows and in letters to newspapers -- several papers have tripled their normal letters columns because of the outpouring -- the Japanese people are saying that they do not want their sons sent to war zones overseas.

Kaifu has suffered as well from external events beyond his control and from his own vacillation in the debates. On one key point -- whether the Peace Cooperation Corps could join U.N. military units -- the prime minister has changed positions repeatedly.

Consequently, it seems highly unlikely that Kaifu can win passage of his bill by his original target date of Nov. 10, when the Diet must recess for weeks because of enthronement ceremonies for Emperor Akihito. He could call the legislature back into session in December or January -- if he still has enough support within his party then to keep his job.

The legislation at issue would permit Japan to send roughly 1,000 people for non-combat duty -- such as transport, truck repair and communications -- with the U.S.-led multinational force on the Arabian peninsula.

This corps would help Japan to quell foreign criticism that it has not contributed enough to the allied effort despite its nearly total dependence on Mideast oil. Indeed, the legislation was drafted largely in response to American suggestions that Japan should send manpower as well as the $4 billion it has pledged for the gulf force and countries hit hard by an economic embargo on Iraq.

But in a wealthy, confident nation that is clearly attracted by the popular slogan that "Japan Can Say No" {to America}, the argument that the cooperation corps is designed to satisfy U.S. pleas has not been politically helpful. Because of his apparent eagerness to cooperate with President Bush, Kaifu recently has been labeled as the "can't-say-no prime minister."

"We find it hard to go back to our constituents and argue for this bill," said Yoshitaka Murata, a Liberal Democratic Diet member.

"At some point, we had to have this debate about our role in the world, half a century after World War II," Murata continued. "But it is very unfortunate it came up now, in response to the gulf crisis, because it looks like we are only acting under foreign pressure."

Even if Kaifu manages to hold the support of his own party, that would not be enough to win passage of the bill in the legislature's upper house, where the LDP is in the minority. Leaders of the Socialist and Komeito parties, the two next most important parties, have both indicated they oppose the bill.

Opinion polls have shown that most Japanese oppose sending personnel to the Persian Gulf, and that opposition has been growing in some polls taken since the start of the Diet debate.

Meanwhile, Kaifu's poll ratings have been dropping. A survey last week by the national newspaper Mainichi Shimbun showed 36 percent of the respondents opposed to Kaifu and 35 percent in favor -- the first time in over a year that "unfavorables" have come out ahead. The rating represented a 10-point drop for Kaifu since last summer.

Kaifu also has to be concerned about consternation in South Asian nations, which remember Japanese conquest earlier in this century and are worried about Japan's sending troops overseas.

Just when Japanese diplomats were trying to soothe those worries, a flap developed around a small East China Sea island chain, known here as the Senkakus. China, Taiwan and Japan all claim sovereignty over the uninhabited islands. But last week a Japanese Coast Guard ship turned away two Taiwanese fishing boats from the islands, making Asian nations shudder again at the thought of Japanese troops around the world.

Another problem for Kaifu is the still smoldering controversry surrounding Japan's justice minister, Seiroku Kajiyama, who recently compared U.S. blacks to prostitutes. Some members of Kaifu's party are blaming him for failing to force Kajiyama's resignation.