SEOUL, DEC. 9 -- With South Korea's presidential election only one week away, antigovernment students and politicians are mounting a last-ditch effort to persuade dissident candidates Kim Young Sam and Kim Dae Jung to agree on a single opposition nominee.

Several hundred students today continued sit-ins and hunger strikes begun last week at the presidential campaign headquarters of the two Kims, calling for either one of the opposition candidates to drop out of South Korea's first direct presidential election in 16 years. Several politicians also stepped up a long-shot mediating bid, said to include South Korea's Catholic primate, that aims at arranging a meeting Friday between the rival Kims.

But even the most optimistic participants in the eleventh-hour reconciliation bids admitted that prospects are bleak for inducing the stubborn Kims to agree on a single candidate to face ruling party nominee Roh Tae Woo. When massive antigovernment protests last June forced President Chun Doo Hwan to agree to presidential elections, now set for Dec. 16, the two Kims promised that only one of them would run. But with each Kim claiming the right to carry the opposition flag into the election, their talks on a single candidacy failed earlier this fall.

"We are desperately trying to do something," said Hong Sa Duk, a member of the National Assembly who is involved in the talks. At Kim Young Sam's party headquarters, where the students unfurled banners from windows and wore headbands urging a single candidate, a student described the stakes in blunt terms: "If we don't have a single {opposition} candidate, Roh will win."

Most political experts in Seoul said a single opposition candidate would be ensured of victory against Roh, a former general hand-picked as the ruling party's nominee by the unpopular President Chun.

The sometimes passionate degree of support for a single opposition candidate was gruesomely illustrated Saturday, when a man burned himself to death to protest the failure of the Kims to unite against Roh. A group of opposition activists have shaved their heads to protest the two Kim candidacies, while some of the students are on hunger strikes.

But few people in Seoul appeared confident that the Kims were prepared to unite at the close of an emotional campaign that has widened regional rifts between their home provinces. Hong, the politician involved in the talks, said he believes the best that can be hoped for is a joint statement in which the Kims urge voters to cast their ballots for the opposition. This would give a semblance of unity, Hong said, shoring up some of the Kims' lost credibility.

So far, Kim Young Sam appears willing to meet with Kim Dae Jung, who has not responded to the offer. Kim Young Sam's reported willingness to meet may stem from his belief that he has the upper hand in the campaign and thus can demand that Kim Dae Jung step aside. Left-wing presidential candidate Paek Ki Wan, who has promised to drop out of the race if the Kims agree on a single candidate, is playing a prominent role in trying to arrange a meeting of the two Kims.