TOKYO, SEPT. 26 -- The race to succeed Yasuhiro Nakasone as Japan's next prime minister has produced three main candidates and a growing concern here that none of them may present to the public here and the world outside the kind of strong leadership that Japan needs to fulfill its role as a world power.

Nakasone, his popularity still on the rise, is preparing to step down Oct. 31 after five years as a new-style, media-conscious, world-traveling prime minister. Diplomats, politicians and in some cases even the candidates themselves acknowledge that the post-Nakasone era is likely to feature a return to the more colorless and cautious leadership style of the past.

"Any of the three who succeeds him will be a very good man and will follow in Nakasone's footsteps, but none of them will be a Nakasone," said U.S. Ambassador Mike Mansfield. "Leaders are not the norm in Japanese politics, in the sense that Nakasone has been a leader."

"People are not enthusiastic about any of them," said one legislator who firmly backs one of the three. "We are coming to a sort of lean years in politics. It's a problem."

The "lean years" come as Japan, more than ever, needs strong, talented leaders, when consensus will not be as easy to achieve as in the past, according to many political experts here. Responding to demands from the United States and elsewhere that Japan open its markets and play a larger world role will entail angering traditionally powerful constituencies here such as farmers and shopkeepers, Seizaburo Sato, political science professor at Tokyo University, said in an interview this week.

Asked whether any of the three candidates to replace Nakasone has the assertiveness to take those necessary steps, Sato said, "No. No one. It's impossible." All of the candidates have been subjected to unflattering descriptions in the press and political conversations. One leading candidate has been likened to "a panda bear with more charm than brains." Another is described as a former English teacher who can barely speak English. And the third is often portrayed as a politically aloof egghead. While these highlight the worst in each of the three candidates, they nonetheless reflect the concern about whether the country will have continued strong leadership.

Public opinion polls have shown lukewarm support for all of the three "new leaders" -- Shintaro Abe, 63; Noboru Takeshita, also 63; and Kiichi Miyazawa, 67, all of whom have held key Cabinet posts under Nakasone. But the new prime minister will not be selected by the public at large, and Nakasone's standing as reflected in the polls also was low before he took office.

Instead, Nakasone's successor is likely to be chosen by a few hundred representatives of the Liberal Democratic Party which has ruled Japan for 32 years. The prime minister is chosen by the Diet, Japan's parliament. The ruling party controls the Diet, and so the internal battle to become party president is also a fight for the prime ministership.

That battle has little to do with ideology or policy. Like Nakasone, the candidates all pledge to maintain a strong alliance with the United States, reduce trade frictions and use Japanese wealth to promote world prosperity.

Instead, the battle is one of factions, Nakasone and his three would-be successors each control one, and the key to victory is to win over members of other factions and the handful of nonaligned members. The weapons are fund-raising ability, support given in past legislative elections, jobs promised in future administrations -- in short, whatever will win over a majority of the 445 ruling party legislators in both houses of the Diet.

Because so few people will decide the race and negotations among the top leaders are so labyrinthine, no one can predict which of the three will win, or whether a dark horse contender might surprise everyone.

"It's like trying to calculate the money inside someone else's wallet," said Liberal Democratic Party Diet member Michio Watanabe, a leader of Nakasone's faction, where some still hope the prime minister might win an extension of his term.

If the internecine battle were as simple as arithmetic, Takeshita, head of the largest faction, would be the man to beat.

Takeshita, a self-deprecating man who taught English briefly after World War II, is a former finance minister known more for his skill as a political infighter than for his interest in complex issues. Currently secretary general of the party, he is said to remember every legislator's year of election and by what margin he won.

"I've had many chances to meet him, and I've never heard him talking about policy or political ideas," said Tsuneo Watanabe, editor in chief of Japan's largest circulation paper, Yomiuri Shimbun, and a friend of Nakasone.

Takeshita's supporters say his political skills are a strength that will allow him to implement policies that Nakasone could only call for. The next leader faces thorny domestic issues, including tax reform and opening Japanese markets to foreign companies, and the Takeshita faction says their man has the political muscle those will demand.

Takeshita recently said in an interview that he sees himself more as a harmonizer than as the formulator of grand new schemes. But with 114 legislators on his side, Takeshita also has the most enemies in other camps. And when some of his youthful troops began bragging last month that Takeshita had the race in the bag, Nakasone, who has yet to throw his prestige or his 87-member faction behind anyone, reportedly was displeased.

Next in strength is Miyazawa, an urbane intellectual who is said to disdain the nitty-gritty of politics. Currently finance minister, Miyazawa is widely supported by business leaders, who view him as the candidate with the best grasp on complex issues and the ability to deal as an equal with the United States.

Japanese newspapers have speculated that Miyazawa is also Nakasone's personal choice, although the finance minister is somewhat more dovish on defense issues than Nakasone has been. Opponents say he would be unable to work his will on the Diet.

Abe, whose heavy dark glasses caused one voter to liken him to a panda bear in a recent poll, controls an 85-member faction. Son-in-law of a former prime minister and foreign minister during most of Nakasone's tenure, Abe is touted by supporters as a blend of Takeshita's savvy and Miyazawa's intellect. But those in other camps maintain that he falls short on both counts, saying he excels chiefly in caution.

Rumors of shifting alliances abound. One has Takeshita and Abe striking a deal that would allow them to serve as prime minister in turn, two years apiece. Another suggests that Abe might link up with Miyazawa instead.

Nakasone is reportedly eager to remain influential once he steps down and even entertains the notion of returning to power some day. So he would like to play kingmaker next month.

"Nakasone wants to cast the deciding vote," said Watanabe, the Yomiuri newspaper editor.

As for an extension of Nakasone's term now, which would require a change in party rules and approval by two-thirds of Liberal Democratic Party legislators, the suggestion is voiced mostly within the Nakasone faction. But it does appear to reflect the lack of excitement the three "new leaders" have generated so far.

Before Nakasone took power five years ago, he was the object of similar lukewarm feelings. He was called the "weather vane," because he allegedly shifted positions to suit his ambitions. Far from well-liked in the Diet, Nakasone was elected only because of behind-the-scenes support from former prime minister Kakuei Tanaka, who had been forced out of office in the Lockheed bribery scandal but, until a recent stroke, remained the kingmaker of Japanese politics.

With the Nakasone history in mind, many Japanese politicians and pundits refrain from predictions about the next prime minister. For now, the only certainty is that Tokyo's ryotei, elegant and expensive dining establishments where political deals are struck in private rooms, will continue to rake in the yen as sake is poured, drivers and cars idle outside and promises are made and, very likely, broken.