THE dramatic declaration of the end of the Soviet Union by the leaders of its three Slavic republics and its replacement by a new commonwealth has provoked a deep political crisis here.Opinions are sharply divided over the wisdom and legality of the statements issued after the Slavic summit on Dec. 8. For Soviet President Mikhail Gorbachev, the almost casual dismissal of the tattered remains of his central government is "illegal and dangerous" and "can only boost chaos and anarchy in society." For the Russian leadership, the treaty between Russia, Byelorussia, and the Ukraine is "the only, and quite possibly the last, chance to avoid what has happened in Yugoslavia," as Russian Foreign Minister Andrei Kozyrev told reporters on Dec. 10. The Russians argue that this was the only realistic basis for retaining links with the Ukraine, whose population voted overwhelmingly for independence Dec. 1 (Slavic confederation, Page 4). Mr. Gorbachev, who has vowed to fight the new treaty, has persistently refused to accept the results of the Ukrainian referendum, just as he doggedly resisted the desire of the three Baltic states for independence. In a Ukrainian television interview on Dec. 8, he reiterated his argument that the voters had not rejected continued political union. In Gorbachev's mind, independence and union can coexist. "Mikhail Sergeivich [Gorbachev] has lost his bearings as to what is going on in this country," said Byelorussian leader Stanislav Shushkevich. "His assessment of the outcome of the referendum in Ukraine was ridiculous. The change in public opinion in Byelorussia is the same as in Ukraine - it is impossible to ingore it." In some respects, Gorbachev's insistence that union and sovereignty are the same thing has pushed the relatively moderate Ukrainian leadership of President Leonid Kravchuk to hold out for a structure in which there is virtually no trace of a central administration. "We should not be blamed for breaking up the union," Mr. Kravchuk told reporters, clearly in response to Gorbachev's TV interview. "We were against only one factor - to have a state to govern us. Ukraine has always called for integration. Today, using their constitutional rights, the three states showed an example of integration, which is similar to the forms existing in Europe." Gorbachev's resistance has angered some in the Russian camp; they accuse the Soviet leader of trying to maintain the old centralized state and his own personal role. "Attempts to protect one's own interests at any cost are typical of the regime that ruled for 70 years," Mr. Kozyrev said. Gorbachev's aide, Georgy Shakhnazarov, said Gorbachev would resign if the commonwealth treaty is allowed to stand. Russian leader Yeltsin tried to mollify Gorbachev in his meeting on Dec. 9 by hinting that he might retain some undefined role in the new commonwealth. In a statement following this meeting, Gorbachev challenged the legal authority of the three Slavic leaders to dissolve the Soviet Union. "The speed with which the document appeared is baffling," he said. "It was not discussed either by the citizens or the parliaments of the republics on behalf of which it was signed." The Soviet leader tried to treat the commonwealth treaty as an alternative draft to his own version of a political union treaty and called on republican legislatures to consider them both. In somewhat more threatening terms, Gorbachev said it is necessary to convene a Congress of Soviet Peoples' Deputies, the supreme legislature of the former Union, or perhaps even call a nationwide plebiscite on the issue. While the leaders of the Slavic republics are clearly trying to avoid a confrontation with Gorbachev, they have firmly rejected such ideas. As for another referendum, Ukrainian leader Kravchuk told reporters on Dec. 9 that "we are an independent country, and we wouldn't hold it." "The Congress of Peoples' Deputies as a supreme governmental authority cannot be considered legal in these conditions," responded Sergei Shakrai, legal counsellor of the Russian government. "Attempts to convene this body and pass decisions would have to be considered unconstitutional. What we have is an attempt at confrontation." Leaders from all three Slavic republics have made it clear that the majority of their representatives to this body, which ceased an active role after the failed coup last August, would refuse to attend any such session. Mr. Shakrai argues that the three Slavic republics have a legal basis for dissolving the Soviet Union, as they are the original signatories of the 1922 Treaty of Union. The only other signatory at that time, the Trans-Caucuses republic, no longer exists in that form, having been broken up into three separate republics. The leaders of the three republics have the authority to do this, Kozyrev argued, by virtue of their own democratic elections. "The true will of the people was expressed in popular, democratic elections. They were relying on a clear mandate," he said. Still, it is clear that Gorbachev and his close aides are preparing to launch an open political struggle against the pact. The meeting on Dec. 9 between Yeltsin, Gorbachev, and Kazakhstan President Nursultan Nazarbayev was apparently a tense one. Gorbachev and Mr. Nazarbayev spent 80 minutes listening to Yeltsin's explanation and arguing with him. Nazarbayev made it clear in a press conference afterward that he was miffed that he was left out of the process. His position is a difficult one. He is the head of a republic whose national population of Kazakhs is a minority, with Russians, Ukrainians, and other nationalities making up the majority. Nazarbayev, who is one of the more effective and popular republican leaders, has been a strong backer of continued union. "It was a big mistake not to invite Nazarbayev," comments Russian parliamentarian Alexander Domrin, a member of the foreign relations committee. "After all, Kazakhstan possesses nuclear weapons," he adds referring to the Soviet long-range nuclear missiles based in the vast territory of the republic. There are fears that the Kazakhs could be pushed into the arms of the four Central Asian republics, whose lack of a role in the new commonwealth may be pushing them under the influence of neighboring Islamic states such as Iran. "In the longer term, there could be the alienation of the Central Asian republics and this could be very dangerous for our security," says Mr. Domrin. The leaders of the new commonwealth have stated, however, that the grouping is open to all participants - not only the former Soviet republics but possibly even former members of the Comecon economic pact, such as Bulgaria and Romania, as well as the now independent Baltic states.