The political future of President Boris Yeltsin was thrown into serious doubt Thursday when he was hospitalized for the second time in 10 weeks with an acute heart condition.


Yeltsin, 64, was taken by helicopter from his country residence outside Moscow to the Central Clinical Hospital, commonly known as the "Kremlyovka," at 2:30 p.m. on Thursday, hospital officials confirmed.


Yeltsin's aides gave conflicting reports on the state of the president's health, but the view given by top aide Viktor Ilyushin at a televised Kremlin press conference Thursday evening was sobering.


"The president's condition does not call for great optimism," said Ilyushin. "It is unlikely that he will be back at work in the near future."


Analysts saw the recurrence of the president's heart condition as throwing a large question mark over his prospects for re-election next June.


There was no indication, however, that Yeltsin's condition had forced him to transfer his powers to Prime Minister Viktor Chernomyrdin.


Ilyushin pointed to Yeltsin's recent visits to Paris and New York as possible contributors to the recurrence of his heart condition, as well as his "indefatigable character." He said Yeltsin's planned trip to China has been postponed, while Tuesday's Bosnia summit in Moscow was in question.


The president's press service tried to downplay the incident, saying that Yeltsin's illness was not as serious as his last attack on July 11.


"His condition is fine, his mood is upbeat," said a press spokesman.


According to the Kremlyovka doctors, the president has acute ischemia, a condition that restricts the flow of blood to the heart, Ilyushin said. "It is probably a continuation of the condition he had this summer."


While a more detailed diagnosis would not be made until Friday morning, said Ilyushin, it was already clear that the president would not need an operation.


Doctors treating Yeltsin would make no predictions as to how long the president would be in the hospital, Ilyushin said. But he added that he saw no need to limit the president's convales was "highly unlikely" Yeltsin would be able to go ahead with the meeting.


Yeltsin's trip to China, which was to take place in early November, has already been postponed.


Yeltsin has been out of the public eye since Tuesday, when he returned from addressing the United Nations' 50th anniversary session and holding a one-day summit with U.S. President Bill Clinton.


While the Russian president had no obvious medical problems during the visit, he walked stiffly, spoke slowly and appeared tired toward the end of his trip.


Chernomyrdin -- who as prime minister would, by law, replace Yeltsin if the president were to become incapacitated -- was continuing his normal schedule, a spokesman for his press office said Thursday.


The Constitution provides three cases in which the prime minister takes over the function of the chief executive: resignation, impeachment or "prolonged inability to carry out his duties because of his health."


If Chernomyrdin were to become acting president, elections would have to be called within three months.


"The president is in charge. There is no indication that he cannot carry out his duties," press spokesman Igor Ignatyev told Reuters. "There is no question of replacing Yeltsin."


But this second attack in such a short period of time could spell the end of any hopes for a second Yeltsin term, analysts said Thursday.


"Who will vote for a sick man?" said Sergei Markov, senior analyst at the Moscow center of the Carnegie Endowment for International Peace. "Once, maybe, it could be explained away, but not twice."


There were now two possible scenarios, added Markov.


Yeltsin could either begin the search for an acceptable successor, or he could cancel presidential elections and strengthen authoritarian control over the country, he said.


Andrei Piontkowsky, head of Moscow's Center for Strategic Studies, sees the problem a bit differently. In his estimation, Yeltsin is now faced with the same choice he had after his first attack in July.


"He can either play the statesman, do what is good for Russia, and groom Chernomyrdin as his successor -- or he can indulge his own ambitions, undermine Chernomyrdin as a candidate and plunge Russia into a catastrophe," he said.


The two analysts were divided over who would be the most appropriate successor for Yeltsin, but they agreed that the choice would depend largely on Yeltsin's close aides.


"Yeltsin's circle is afraid that a new president would send them to prison," said Markov. "They would have to answer for the storming of the White House [when tanks fired on the parliament in October, 1993], for the collapse of the Soviet Union, for illegal privatization."


The bottom line, both analysts said, is that Yeltsin will be unable to stand for re-election.


"He cannot run again," said Markov.


On the streets of Moscow, reaction to the president's latest incapacitation was mixed.


"I wish a speedy recovery," said Vladimir Budov, 39, a chemical engineer interviewed outside Belorusskaya metro station. "But even if the president dies, I think the country will be all right."


"I am afraid the leftist movements, the communists with [their leader Gennady] Zyuganov, may take advantage of the situation. At least today Yeltsin offers some kind of stability," said Yelizaveta Kopova, 54.


Her concerns were not shared, however by pensioner Varvara Fyodorova, 70: "I am not interested in any news about Yeltsin. Life is very hard under him. Even without him it can't get better. Even during the war we had a better life."


aFor the past eight years, the health of Boris Yeltsin has attracted world attention, and given rise to wide speculation about his drinking habits and boisterous lifestyle. Some of the major events in his health history are listed below:





November 1987 -- Yeltsin is hospitalized for chest pains and nervous exhaustion after his dismissal as head of the Moscow Communist Party organization.





October 1989 -- During a trip to the United States, Yeltsin appears in an obvious state of intoxication. During this year rumors of his alcoholism begin to circulate in earnest. In one notorious incident, Yeltsin falls into the Yauza River. He blames the fall on a terrorist attack.





August 1991 -- On the eve of the failed coup Yeltsin was reported to have been "untransportable" from Almaty to Moscow on account of drunkenness.





October 1991 -- Yeltsin takes two weeks' rest after suffering what his aides called minor heart trouble.





March 1993 -- In a speech before the Ninth Congress of People's Deputies, Yeltsin appeared dishevelled and slurred words. Deputy Vladimir Isakov called for a medical commission to assess his health.





September 1993 -- Yeltsin summons a Spanish surgeon to Moscow to treat his back problem incurred during a rough helicopter landing in Spain in 1990.





February 1994 -- Sidelined for two weeks with flu, Yeltsin postpones his state of the nation speech.





March 1994 -- Yeltsin retires to Sochi, stricken again with flu. An aide calls rumors of his bad health "insulting." The U.S. television network NBC reports that Yeltsin has cirrhosis of the liver which could be fatal.





August 1994 -- A wild Yeltsin creates a scandal on a visit to Berlin, seizing a conductor's baton and blowing kisses to the crowd.





September 1994 -- En route from the United States to Moscow, Yeltsin "sleeps through" a scheduled meeting with Irish Prime Minister Albert Reynolds at Shannon Airport. On arrival in Moscow, Yeltsin says he "overslept." "It just happened -- what can one do?" he says.





December 1994 -- On the eve of the Russian attack on Chechnya, Yeltsin enters the hospital, ostensibly for minor nasal surgery. He is released only after 10 days.





February 1995 -- At a CIS summit in Almaty, Yeltsin has to be supported by aides on entering the hall and is visibly disoriented.





April 1995 -- Yeltsin prolongs a vacation by one week. No explanation is given.





July 1995 -- Yeltsin is rushed to the Kremlin hospital with what doctors call "acute heart problems." The diagnosis is later refined to ischemia, a condition that restricts blood to the heart. Yeltsin's convalescence lasts for a full month. Communist Deputy Viktor Ilyukhin repeats calls for official and public reports of Yeltsin's health. One week later, Yeltsin says he has had a "heart attack."





Oct. 26, 1995 -- Yeltsin is again hospitalized for ischemia. While his aides say the president is feeling well, his wife Naina says Yeltsin will have to have proper treatment "sometime."


-- The Moscow Times