South Korea has this problem with its presidents.

One of them was shot. One was exiled. Two were overthrown by coups, two others hauled off to prison.

"It's embarrassing," said a government official.

The only ex-president not on that list now seems determined to carve his own mark of dubious distinction. At a time when politics-weary South Koreans yearn for a gracious departure of some of their aging leaders, Kim Young Sam just won't shut up and go away.

Kim, who was president from 1993 to 1998, is determined to deflate the heroic international stature of his successor, President Kim Dae Jung. The former president accuses the current president of being a dictator, practicing oppression, media control and wiretapping.

"He has intentions to continue in political power forever," Kim Young Sam said. To prevent that, Kim said he wants to reenter the political arena to battle his old rival before next April's National Assembly elections.

His animosity to Kim Dae Jung is clear. The two men have been rivals for 40 years, sometimes cooperating in the ever-shifting calculus of Korean politics, sometimes competing, but rarely friendly.

But his stinging accusations against Kim Dae Jung, the man known as "the Nelson Mandela of South Korea" for his long struggle against dictatorial rule, makes a lot of South Koreans cringe.

"People want Kim Young Sam to be quiet and write his memoirs," said Jay K. Yoo, a member of the National Assembly.

But even as they wince at the blunt language, a surprising number of Koreans say they agree with the gist of Kim Young Sam's charges.

Despite his reputation, and despite his steady handling of the South Korean economic crisis in his first 18 months in office, there is a sense of disappointment in Kim Dae Jung, according to politicians, analysts and citizens on the street.

His popularity within South Korea has dropped. His ruling coalition is fraying. And opponents such as Kim Young Sam sense a vulnerability that has caused them to hone their political knives.

"I believe President Kim has turned his back on his past," said Lee Hoi Chang, president of the opposition Grand National Party. Kim, he said, has fallen into "regionalism, cronyism and boss politics."

The immediate causes of Kim's popularity decline, his supporters acknowledge, are the corruption scandals that started bedeviling the Kim administration last spring.

Kim's economic adviser was dismissed when he could not explain why a burglar had found $100,000 in his home. The justice minister was fired for fomenting a strike after barely surviving an uproar over his wife's acceptance of a fur coat from a jailed tycoon's spouse. The environment minister, actress Sohn Sook, was dismissed in June for taking a $20,000 cash payment from a Korean businessman. Last month, another Kim protege and his wife were charged with taking $400,000 in bribes from a banker.

Adding to the scandals is the sense that President Kim, 73, is wielding power with the same political ruthlessness of his predecessors. Critics say he has packed government positions with his home-region supporters, targeted opponents for investigation, leaned on the news media and favored certain business groups. And he appears ready to back out of a pledge to support a parliamentary system of government by the end of this year.

"He has set the moral standard higher," insisted Park Jung Ho, the president's press secretary. "From the beginning, he said he will make a corruption-free society. But he can't do it right away." As to the other charges: "Kim Dae Jung was a defender of human rights and liberty. He was a symbol. So if there's any case of freedoms being violated, he would not tolerate it."

But the whiff of politics as usual has soured some South Koreans who had expected something different when they elected--for the first time--an opposition party led by a man who had put his life on the line for democracy.

"I am very disappointed in him," said Juang He Cho, a 38-year-old computer programmer. "This last time, I finally decided to vote for him because I really thought it would bring change. It hasn't."

That is where Kim Young Sam reenters the stage. A stout 71-year-old with a silky wave of gray hair, Kim Young Sam said he expected to be content to accept political retirement, enjoying the life of a grandfather in his elegant Seoul house lined with pictures of himself with world leaders.

But Kim said the more he saw the "suppression" of democracy by his successor, the angrier he got. And when Kim Dae Jung boasts of reversing the economic and political ills he inherited, Kim Young Sam steams.

"He's blaming everything on me," complained Kim Young Sam. In that, though, President Kim is repeating conventional wisdom. When the economy collapsed with stunning swiftness in November 1997, Kim Young Sam was widely reported at the time to have been helpless--and former aides concur.

Kim Dae Jung, who had been elected but had not taken office, stepped in in an extraordinary unofficial assumption of power, and began working with the International Monetary Fund to restore the economy's health. Many, though not all, economic indicators and the South Korean stock market have rebounded.

But Kim Young Sam complained that "DJ," as the president is known, "is responsible for 50 percent of the failure of the economy"--for positions he took while in the opposition. What angers him even more, he said, is the "retribution politics" he said the current administration is practicing.

Special correspondent Joohee Cho in Seoul contributed to this report.