SEOUL, JUNE 23 -- Political concessions being readied by President Chun Doo Hwan are aimed at breaking up an unusual alliance of radicals and ordinary citizens who in the past two weeks have mounted the greatest challenge his 7-year-old government has faced.

Offers to free prisoners and begin talks with the main opposition party are dismissed as meaningless by many of the radical students who have been battling the police. They want nothing less than Chun's overthrow.

But Chun's government is hoping the steps will satisfy opposition politicians, as well as ordinary citizens who have supported the students since they took to city streets on June 10.

"The majority of the people, including the middle class, will be inclined to support the measures taken by the government," said Choi Chang Yoon, vice minister of culture and information.

Without that support, the reasoning goes, the protests in the cities will die out, and radical students will revert to what they were before the crisis: a noisy minority that police can contain inside campus gates.

From the start, the demonstrations have been without real leaders. The government is now seeking a deal with the opposition Reunification Democratic Party and its president, Kim Young Sam, in large part because there is no one else.

Many people in the streets will not feel bound by any deal forged by Kim, though he will have some moral authority in appealing for cooperation. His party did not organize the protests. Indeed, he has expressed as much surprise as anyone that they have gone so far.

Student activists here fight under the banners of a constantly changing tangle of councils, fronts, federations and associations, some legal and officially recognized, others outlawed as subversive. Factions rise and fall and feud with each other.

At present, at least two underground groups, the People's Democratic Fighting Committee and the Self-Reliance Democratic Fighting Committee, are tussling for control of the opposition movement's extreme left wing.

Few rallies occur spontaneously, The riot police almost always have advance notice. Posters are displayed. Fliers are passed out and the news spreads by word of mouth. Most demonstrations involve only a single campus. Occasionally, however, student representatives from around a region or city meet secretly to map out plans for everyone to mass at one campus. Highway rest stops are sometimes used for such talks.

The results can be impressive. Today, about 20,000 students from the Seoul and Inchon areas got together at Yonsei University in Seoul for a peaceful antigovernment rally.

Christian activists are also split into many factions. The Korean National Council of Churches, a strong voice in many antigovernment causes, represents only about 40 percent of the country's 8 million Protestants. Conservative groups speak for the rest.

When a protest is coordinated nationally, it is usually a political party or a single-issue organization formed for the purpose that is responsible. The June 10 protests that touched off the current wave of demonstrations, for instance, were organized by a group called the National Coalition for a Democratic Constitution, linking students, churchmen, politicians and labor leaders.

Many students deeply distrust Kim Young Sam and another prominent dissident with whom he shares control of the party, Kim Dae Jung. They are seen as ambitious, self-serving men who are as much a part of the political problem as Chun.

"Civilian fascists" is how one student organizer at Yonsei University described them.

"The opposition party compromises with Chun if that benefits their political goals," he said. "Students don't want compromise. They want to root out dictatorship."

Even students who do support the Kims as successors to Chun do so half-heartedly. "If they get power, they should be ready to transfer it to the next generation soon," said a student from Pusan's Dongeui University who has been active in the street demonstrations.

During a rally in Inchon city last year, protesters approached Kim Young Sam on the street and rudely told him to leave. Last week, envoys from his party got similar treatment when they went to a Catholic cathedral in which students had taken refuge from police.

The government hopes that the citizens who have been donating food, drink and cash to the demonstrators will now lose interest, stop regarding the government as unreasonable and resume regarding the students simply as radicals rather than principled people with courage enough to speak their minds.

Some people on the opposition side concede this may happen. One Christian official suggested that after two weeks of tear gas and turmoil, people are tired.

"Most people are thinking a big demonstration has taken place," he said. "The government knows what the people feel and it will revise its policies. The best thing to do is to wait and see. If we are cheated, we can go out on the streets again."

But he noted that young people are pushing for more street action right away.

Street protests have fallen off in South Korea in the past several days. Many people take this as evidence that the government's approach is working. There is growing optimism among many ordinary Koreans that changes are ahead.

"I think there will be an important decision for more democracy," said an airline ticket salesman.

But there also is evidence that the government's tactics are not working.

The National Coalition for a Democratic Constitution has announced it will hold a "grand march for peace" in Seoul on Friday. The government is not serious, members say, and needs more pressure.

Kim Young Sam and Cardinal Stephen Kim, leader of the country's Catholics, have asked that the march be postponed. They say it will harm chances for compromise. So far they have been ignored.