He is the one likely successor to Leonid Brezhnev who speaks English, has lived abroad, plays tennis and cultivates a man-of-the-world image different from a dour provincial apparatchik's. He is fond of cynical political jokes with an anti-regime twist. He collects abstract art, likes jazz and Gypsy music, dances the tango gracefully and, most unusual, he has a record of stepping out of his high party official's cocoon to contact dissidents.

His name is Yuri Andropov, and Soviet emigr,es describe him as the smartest and the most cultured man in the upper reaches of Soviet power -- as well as the cunning strategist who throttled both the human rights and the Jewish nationalist movements. The American assessment is similar but based on second-hand information since, for the past two decades, no American official has spoken with him.

But, according to U.S. intelligence, Andropov has a serious heart problem and has had a heart attack. And most observers believe that in his bid for the top job he is handicapped by the fact that he was the KGB's boss for the past 15 years. The KGB may guard the paperpushers of the Communist Party from enemies at home and abroad, and under Brezhnev the secret police did not liquidate party members. However, party rank-and-file are historically uneasy with the idea of having as their secretary general a secret police chief who once bugged their conversations and kept files on them.

There is bound to be jealousy as well. The party is watched by the secret police. But there is no KGB looking over the shoulders of the KGB, and thus, as strange as it may sound, the KGB is the freest and most independent organization in the Soviet structure. And it is conceivable that keeping in close touch with dissidents at home or observing the great wide world abroad affects KGB agents. Under Andropov's worldly stewardship, the KGB might have become a safe place for closet liberals, just as the CIA was a good place for American liberals during the years of McCarthyism.

Sharply tailored in a West European style, Andropov is about 5 feet 8, handsome with receding silver hair and a good public speaker. He has impressed party audiences by being able to deliver a speech without notes. He is an ethnic Russian, a native of Karelia, an autonomous Soviet republic bordering Finland, the son of a railway worker and a party member since 1939.

His star is clearly on the rise. He is 67, which is about the average age in the Politburo, the party's l4-man board of directors. Last week he was appointed to succeed Mikhail Suslov, the party's chief theoretician who until his death this January held the rank of Central Committee secretary. The only other Politburo members who have the rank of Central Committee secretary are Brezhnev -- whose title of general secretary means that he is Number One -- and the two other candidates for the top job most frequently mentioned: Andrei Kirilenko, 75, and Konstantin Chernenko, 70.

Over the past two years or so, Chernenko emerged as Brezhnev's personal choice as his successor. But Western observers doubt if Brezhnev has the power to install as his heir a man who is seen by their comrades as his crony and valet.

Andropov is the only Soviet leader believed to have had direct contacts with Soviet intellectuals critical of the party line. Once in power, he could prove the paradox of a secret police chief being more reform-minded than the party he was to protect from reformers.

According to accounts U.S. experts consider reliable, on several occasions in the past 10 years Andropov invited leading dissidents to his home for well lubricated discussions that sometimes extended to the wee hours of the morning. Andropov also encouraged his high-ranking subordinates to contact some key dissidents and conduct correct, even friendly conversations with them.

At a private meeting in Washington a few years ago, one highly respected dissident revealed that in the early '70s he had met with Andropov, whom he described as well read, westernized and a perfect host who even sent a car to pick him up and to return him home. Contacted in Jerusalem, the dissident now denies having met with Andropov, but acknowledges meetings with KGB officials serving just under Andropov.

According to a story spread in Moscow by the poet Yevgeny Yevtushenko and repeated by his friend the novelist Vasily Aksyonov now living in Washington, Yevtushenko had had a friendly relationship with Andropov and called on him to protest Alexander Solzhenitsyn's arrest. Prior to the meeting, Yevtushenko fortified his spirits with vodka, and Andropov's reply to his anguished appeal to free Solzhenitsyn was a chilly dismissal: Call me again when you are sober.

U.S. government experts who debrief emigr,es report hearing of several cases of direct contact between Andropov and dissidents -- but also an unwillingness on the part of the emigr,es to acknowledge those contacts publicly. One veteran U.S. expert says he has "no reason to disbelieve" a dissident's account of a deal Andropov personally arranged with him. The dissident publicly apologized for his "mistake" of joining the human rights movement, and denounced it as fomented by the West; he was then released from jail, and left the Soviet Union with his wife, who was freed from a labor camp.

Dissidents consider Andropov the inventor of the sophisticated policy of granting exit permits to Jews (and later ethnic Germans and Armenians) who wanted to leave and of expelling dissidents who would have preferred to stay in the Soviet Union. Of course only a fraction of the Jews who wanted to leave could leave, and not all the exit visas to Israel were forced upon non-Jews. What the KGB accomplished was uncertainty and division in the enemy camp. But by pursuing a strategy instead of simply saying "nyet," Andropov came out looking like "a liberal by comparison" -- a term used by emigr,es such as Aksyonov.

Some of the rumors about Andropov were spread deliberately, says Aksyonov, once a bestselling novelist in the Soviet Union. He is particularly suspicious of the authenticity of a pledge that Moscow gossip attributed to Andropov: I will not use terror as long as I am head of the KGB. Another statement, accepted by Jewish activists as authentic, has Andropov saying to his agents: Don't look for conflicts with dissidents. In his public appearances Andropov took the position that the opposition to the party was minuscule, and the few people who joined it were psychologically unbalanced, in fact out of their minds.

Soviet dissidents identify Andropov as the only Soviet leader with an appreciation for abstract art. Rumor has it that he has a large collection. On one occasion he sent a message to a prominent Soviet artist expressing his interest in buying a few paintings. The artist responded by asking for a car instead of money, and, according to the story, the car was promptly delivered.

"Andropov looks like a European gentleman and has the highest IQ in the Politburo," says Boris Vinokur, who met him several times as a Soviet journalist. Vinokur now lives in Chicago, where he edits a Russian-English newspaper called Neighbor. He says: "Andropov is the cleverest of them all. And maybe the most dangerous."

"In Stalin's time the KGB was just secret police, but under Brezhnev, the KGB assumed political power and ideological responsibilities," says geneticist Zhores Medvedev, a dissident who now lives in London. "Under Stalin and Khrushchev, the KGB was only repressive, but Brezhnev let it become a policymaking body."

Andropov made the KGB into an organization in charge of analyzing political developments in the capitalist world and the developing countries, Medvedev says. If Andropov becomes Brezhnev's heir, Medvedev predicts, there would be collective leadership, flexibility with China and detente with the United States, if Washington showed interest. Medvedev disagrees that the KGB job is an impediment to Andropov's ambitions; on the contrary, he argues, party apparatchiks enjoyed a high degree of security under Andropov and are grateful to him.

There are Kremlinologists who find Andropov's cozying up with the enemy hard to believe, but they are uncertain whether the rumor is just another emigr,e tale or part of Andropov's strategy to project the image of thoughtful tolerance.

One American Kremlinologist who rejects the idea of Andropov's liberalism is William Hyland of the Carnegie Endowment for International Peace, a former National Security Council aide. Hyland argues that no one can preside over the kind of bloody thuggery the KGB specializes in and be genuinely in favor of doing away with that thuggery.

According to Hyland, Andropov was originally named to head the KGB to give the dreaded secret police a lower profile. After Nikita Khrushchev's revelations about Stalin's crimes and the execution of Lavrenty Beria, Stalin's last secret police chief, the KGB was becoming a scapegoat even within the party. Andropov seemed a genial, nonthreatening type who could correct that trend, Hyland concludes, and he did a good job.

Prior to his appointment to the KGB, Andropov was in charge of the Central Committee department dealing with foreign Communist parties in power. This was between 1957 and 1967, and, according to Medvedev, Andropov surrounded himself then with well educated young people who spoke Western languages and had liberal inclinations. He visited bloc countries at least once a year, usually stayed in resorts such as Marienbad in Czechoslovakia, and he played a good game of tennis. In every East European country he made dozens of friends, and he was considered a good companion who liked to tell -- and listen to -- jokes critical of the Communist system. He considered cynics "his type of people." The country he preferred to visit was East Germany.

As early as in 1953, Andropov, then a junior Foreign Ministry official, was sent to observe the fighting on the streets of East Berlin. And he accompanied Brezhnev in the negotiations with the Czech government that led up to the Soviet invasion in 1968.

For years Hungarian officials have singled out Andropov as strongly supportive of the gradual political and economic liberalization under Party Secretary Janos Kadar, and as their best ally in Moscow against those arguing for re-Stalinization. According to Medvedev, the Soviet party leadership credited Andropov with a consolidation of Soviet influence in Eastern Europe.

The assignment to oversee East European parties, considered a choice job among apparatchiks, was his reward for his performance as ambassador to Hungary between 1954 and 1957. It appears that Khrushchev gave Andropov high points for his moves during and after the 1956 Hungarian uprising, which shook the Soviet system as much as Solidarity's challenge in Poland these days. Some Soviet emigr,es believe that Andropov became the party's specialist in dealing with dissent in Hungary, and his intellectually formative years were the ones he spent there.

Known in Budapest as "The Proconsul," the Soviet ambassador had direct telephone lines to key cabinet members. His word was final on policy as well as personnel changes in the leadership. A word from him, and the forced collectivization of farms was speeded up or slowed down, work on the capital's Metro began or stopped, and people were purged or promoted.

Andropov quickly established himself as a lover of Gypsy music, the more sentimental the better. The favorite song he always asked for was a tearjerker about a bird saying goodbye to his nest. He had a Gypsy band play at parties and receptions, which were usually restricted to officials from bloc countries. On the dance parquet, he cut a dashing figure, and he followed the prewar protocol in asking wives of officials for turns. He is remembered as an accomplished dancer of the tango, as well as the waltz and the Hungarian csardasWashing.

When, after Khrushchev's secret denunciation of Stalin in February 1956, Hungarian intellectuals began their open criticism of Stalinist policies, Andropov invited party members then known as "reformers" for conversations which were always cordial -- the opposite of the stiffly formal sessions party leaders were accustomed to with Moscow's representatives. The people Andropov befriended included Kadar, just after he was released from jail, and Imre Nagy, immediately after he emerged from disfavor.

"Andropov gave the impression of being pro-reform," remembers Sandor Kopacsi, head of the Budapest police during the uprising and now a resident of Montreal. "He smiled often, had honeyed words for reformers, and it was hard for us to tell whether he was only acting on instructions or he followed his own personal inclination. He was well mannered and personable. Instead of ordering this or that, as his predecessor had done, Andropov always 'suggested' and 'recommended' things. But I felt something cold in him. His eyes seemed to change colors, and there was a chilly flame in those eyes hidden behind the spectacles."

During the revolution, Andropov's diplomacy followed two tracks: He kept assuring Hungarian leaders that the Soviet Union contemplated no invasion and he demanded protection for Soviet installations and private citizens. He offered his "personal guarantee" to Premier Nagy and to individual cabinet members that whatever Red Army troops were being brought in were only routine replacements for "tired" units. He maintained a genial, I-am-a-friend-of-the-Hungarian-nation atttitude even on the day of the final invasion, Nov. 4, 1956, when he assured Nagy that no invasion was under way.

"He was a man exuding self-confidence -- decisive, muscular, robust," remembers Gen. Bela Kiraly, chairman of the revolution's military forces and now a history professor at Brooklyn College. "He was masterful in conveying the impression of being sincere and natural."

Kiraly visited Andropov after a complaint to Nagy that "rowdies" threatened to attack the Soviet embassy. Kiraly rushed to the scene with troops but found the neighborhood deserted, and Andropov told him that the call about the rowdies had been a misunderstanding. Andropov assured Kiraly of the friendship the Soviet people felt for the Hungarian people and wanted to know when the Hungarian cabinet would respond to a Soviet proposal for negotiations.

Kiraly remembers that Andropov accompanied him to the embassy's wrought iron gate and shook hands vigorously and at length, with both hands firmly grasping his.

Kiraly's colleague Kopacsi last saw Andropov in a building where the Soviets invited the Hungarians for armistice negotiations. Kopacsi was surrounded by KGB officials taking him to prison when he suddenly noticed Andropov at the top of a staircase, a jovial smile on his face, waving a cheerful goodbye.