China Locked in Struggle. Party's failure to enforce order in the face of massive public protest may impel changes at the top. IN SEARCH OF LEADERSHIP

`YOU had better leave our country,'' the young man at one of Beijing's rebel barricades said. ``There will be a civil war. Maybe some People's Liberation Army soldiers will support the students, and some will be against us.'' The views of one student on the street in the heart of a Beijing controlled by antigovernment protesters may be extreme, but they hit at the heart of the political issue gripping China.

So far, as of press time, students and their supporters among the workers and families of Beijing, have prevented the government from working its will to end the open revolt that has virtually brought the city to a halt.

Indeed, the turmoil in all the country's major cities is likely to bring a further shakeout among the top leadership. The question is who will eventually take the reins of power.(Soviet views of leadership struggle, Page 3.)

Conservative Premier Li Peng has grabbed power and apparently banished his main rival for control of the country, Communist Party General Secretary Zhao Ziyang to the side lines. But his inability to enforce his declaration of martial law may have already made his position untenable. Many Chinese say Mr. Li Peng has lost an intolerable amount of that most precious of commodities in Chinese politics - face.

The Army has been unable or unwilling to follow Li's directions, which outlawed demonstrations, public speeches, and the activities of foreign correspondents. For the most part, soldiers have allowed students and supporters to keep them out of the city.

Yesterday, according to wire reports, 300 students on bicycles rode from Tiananmen Square, the heart of the antigovernment rebellion, to meet a 13-car troop train which arrived unexpectedly at the station here.

The students blocked the main exits of the station and vaulted ticket barriers. Witnesses said the soldiers, armed with automatic weapons, did not try to leave the train. Small groups of police at the station made no attempt to interfere. Crowds continued to throng the square where students were on the ninth day of a hunger strike.

(Meanwhile, in Hong Kong, an estimated 300,000 people jammed streets yesterday in a massive outpouring of support for Beijing's pro-democracy struggle.)

Chinese and foreign observers openly wonder how long it will take Li to resign. The premier is an unpopular man. Much of the chanting of slogans and banner waving has been directed against him. He is held responsible for the slowdown in both political and economic reform this year.

Li has frequently accused the more moderate Mr. Zhao of pushing too hard and too fast with his reform program. Late last year, Li gained the upper hand when spiraling inflation forced the leadership into putting the reforms into abeyance. He was responsible for a series of austerity measures aimed at slowing the overheated economy, which was as unpopular with the people as the inflation it was designed to cure.

While a youngster among China's leaders at just 60 years old, Li has proved himself out of touch with the people.

The only obvious alternative to Li is Zhao. But Zhao has not been seen or heard of since it is believed he was forced to resign late last week after he differed strongly with the standing committee of the Politburo over the decision to send in troops.

But some observers say Zhao is waiting in the wings to make his comeback. They say he may have resigned to purposefully distance himself from the decision. There also have been reports that Zhao is being held under house arrest.

While Zhao is seen here as powerful man, it is uncertain how much influence he wields where it really counts - with the generals. The conventional wisdom is that control of the Army is vital to control of China, and Zhao is deputy chairman of the Central Military Commission.

``Zhao is very powerful,'' says one observer, ``but who will the Army support? They want someone at the helm who can clearly control the country, but they may refuse any order to attack the people.''

It seems the people support Zhao, at least in the absence of any credible alternative. Zhao has at least been spared the ridicule dished out to both Li and senior leader Deng Xiaoping.

``Most of the students and people from all walks of life support Zhao as top leader. They think Zhao was very gentle. After this confusion maybe he will appear in Tiananmen Square,'' to take control of the government, one student says. Zhao's goals are much the same as those of the students who began this month of protest - a reformed, more democratic, and less corrupt China.

Ironically, Zhao has been dropped from power in the same way as his predecessor two years ago. Hu Yaobang, who's April 15 death sparked the demonstrations, was forced to resign from his position as party leader after a wave of student unrest.

Noticeably absent among the banners and chants of demonstrators has been the name of an alternative leader. According to one observer, this is because the Chinese hear only about the people who are actually in control.

``They don't know who else there is,'' he said. ``But these people are genuinely upset. They do not like Li Peng and they do not like the situation. This is the only way they can vote.''

The shake-up in the leadership may well be far from over.

``The reckoning must come,'' says one diplomat, ``and it's odds on that Deng must go. I can't see how the leadership can go on - but it's not the end of the Communist Party - they're [the students] not calling for that.''

Another diplomat says public opinion swung firmly away from Deng in recent months and the 84-year-old leader is now seen as an obstacle to reform rather than a supporter.

``The people identify him with the country's lack of optimism, a feeling of sullen depression, and the ancient man at the top is blamed for it all.''

This diplomat says it is by no means clear yet who will control China when the dust settles from this dispute.

``A lot of people are trying to ride this particular tiger. It remains to be seen who falls off and who stays on.''