Despite tough questioning in parliament and incessant battering from the press, Prime Minister Zenko Suzuki seems to be surviving the political crisis centered on American nuclear arms.

He has managed to stay afloat by insisting, in the face of considerable contrary evidence, that U.S. nuclear arms never have been brought into Japanese waters or stored on Japanese territory.

He is not quelling suspicions, but by stolidly claiming they are untrue, and by refusing all suggestions that he investigate them he is managing to hang on. There's nothing fancy in his footwork -- merely a dogged absorption of punishing blows.

In parliament today, the opposition demanded that Suzuki's government investigate every American base in Japan to determine whether nuclear bombs had ever been stored at any of them. He rejected the idea.

He was called on to send a mission to the United States to find out the truth. He said no.

The opposition wanted to summon former Pentagon official Daniel Ellsberg to Tokyo to expand on a statement that nuclear weapons were once stored offshore from a U.S. Marine base near Iwakuni. It would not be worthwhile, Suzuki said, because Ellsberg is merely a private citizen.

The prime minister, who last week seemed to be teetering, has been able to survive primarily because his Liberal Democratic Party has kept its own doubts to itself and refused to enter the brawl.

The party has large majorities in both houses of the parliament and can sustain Suzuki in office as long as the government is not forced to admit that it and its predecessors have been lying for two decades about the nuclear bomb issue. Normally a faction-ridden organization, the party has presented in public a solid wall of acquiescence to Suzuki's policy of riding out the storm.

Even those who do not like or trust Suzuki do not want to see his government fall, reducing to tatters the reputation of a succession of prime ministers, and risking their own political lives in an election involving the most emotional issue in Japan.

Privately, they have a lot of misgivings. "Frankly speaking, Reischauer is right," acknowledged one Liberal Democratic Party member when asked to comment on former ambassador Edwin O. Reischauer's observation that American warships have always had the right, with tacit agreement by Japanese leaders, to bring nuclear weapons into Japanese waters and ports.

"But the government has decided to go along with the previous promises and to deny [the remarks of] Reischauer. I personally think that we should sometimes say frankly what the real situation is. But the government says, 'No, not yet.' Now that Suzuki has denied it, he is stuck with it. He cannot change unless he leaves office."

Liberal Democrats have thrown out hints that they think the issue of ship-borne nuclear weapons must be clarified somehow -- but not now. There is no way to do it without precipitating a factional brawl, and among the major party factions there is no consensus on a replacement for Suzuki.

The case against Suzuki's story largely has been presented in the Japanese press, which, through interviews with former officials, has more or less substantiated Reischauer's assertion that American warships have been free to bring nuclear weapons into port and into Japanese waters.

Editorially, the papers have persistently called for the government to press U.S. officials for an explanation and blamed both governments for stonewalling with simple denials.

There has not, however, been an outbreak of public hostility to the revelations. In the 1960s, the merest hint that nuclear weapons were sailing into Japanese ports would have produced massive street demonstrations. There have been a few minor demonstrations and political leaders in the port cities where American ships dock have been forced to demand explanations, but so far the outcry has been largely limited to parliament and the press.