Leadership tussle leaves Gorbachev rival down, but not out. MOSCOW SHOWDOWN

Soviet politics have suddenly become dramatically polarized. Supporters of radical reform are now openly describing Yegor Ligachev, the second-ranking Soviet leader, as their main ideological opponent. He is backed, they say, by the enormously powerful Communist Party bureaucracy. And they predict that a showdown will come in the next two months, as the leadership prepares for a nationwide Communist Party conference.

In an interview Tuesday, one outspoken supporter of Soviet leader Mikhail Gorbachev's reforms, Vasily Selyunin, expressed disappointment that a recent bitter dispute over reform played out in the Soviet press did not result in Mr. Ligachev's resignation.

The dispute began with an article that appeared in the newspaper Sovietskaya Rossiya on March 13. The article, signed by a Leningrad teacher, Nina Andreyeva, was later denounced in the Communist Party newspaper Pravda as a ``political platform'' for anti-reform conservatives.

The Pravda rebuttal was reportedly followed by a Politburo rebuke for Ligachev, who had previously expressed support for the article. (Soviet sources critical of Ligachev, now reportedly on vacation, say they see no sign yet that he has lost any official portfolios as a result of the conflict.)

Radical reformers in the leadership apparently lacked either the strength or the resolution to remove him, he noted.

Mr. Selyunin described the Andreyeva affair as a ``well-organized provocation'' and a ``plot against Gorbachev.''

It was strongly reminiscent of the overthrow of Soviet leader Nikita Khrushchev in October 1964, he said: ``We survived by a miracle.''

The latest attempt to derail reform will not be the last, Selyunin predicted. There is a ``precarious balance of power'' between reformers and conservatives. This largely favors the conservatives, he says: They only need to maintain the status quo, while reformers want to transform the system.

Drawing a parallel with Poland's current leader, another prominent reformer commented this week that conservative Soviet leaders want ``a Jaruzelski [Polish leader] - someone who will stop the liberal trend'' in reforms. Ligachev, the reformer said, fits this mold.

Selyunin gave the following account of the origins of the March 13 article:

``There was no Andreyeva article,'' he says. There was simply a letter to Sovietskaya Rossiya ``on two small pages'' from Ms. Andreyeva. The paper's editor, Valentin Chikin, then ``sent one of his best journalists,'' Vladimir Denisov, to Leningrad to write the article that appeared under Andreyeva's name. Mr. Chikin himself made some additions.

The timing of the article was so propitious for conservatives that it is difficult to believe that it was purely coincidental, says Selyunin. Mr. Gorbachev and Alexander Yakovlev, the Politburo member who is believed to be the initiator of many reforms, were both preparing to leave the country.

Problems were still simmering in the Armenian enclave of Nagorno Karabakh. And a controversy was still swirling around a plane hijack.

These grim events were helpful to the conservatives, Selyunin believes. ``Opponents of perestroika need a failure,'' he said. ``They need, so to speak, their own Reichstag fire'' - an allusion to the 1933 burning of the German Parliament, which was used by Hitler as a means to consolidate his power.

Immediately after the article appeared, Ligachev singled it out for praise in two unpublicized briefings with selected representatives of the Soviet news media. And party bodies in many parts of the country called meetings to discuss the article, thereby creating the impression that it was a reflection of the leadership's views.

The official press has since noted that one meeting in support of the Andreyeva article was televised in Leningrad.

Usually well-informed sources say that during other such meetings in Leningrad, speakers referred to ``gross [political] errors'' by Gorbachev. The party chief for Leningrad, Yuri Solovev, is a member of the Communist Party Politburo. Meetings of local Communist Party organizations were called in numerous places around the Soviet Union to discuss the letter.

One person who encouraged discussions, Selyunin says, was Sergei Manyakin, a Central Committee member and head of the Soviet government's committee of popular control.

Selyunin and other radicals note that Gorbachev has been fighting back vigorously. In three separate meetings last week Gorbachev spoke to regional party leaders from around the country. Soviet sources note what they say is the unprecedented fact that the meetings were officially described as being called personally by Gorbachev - not in the name of the party leadership.

The meetings were marked by ``lively'' discussions, says a Soviet source who spoke to some of the participants. Gorbachev explained to the party leaders that there would be no retreat from perestroika, as the present reform program is known.

Radicals say the pressure on conservative leaders should be stepped up. They are calling for the top party leaders to be more ``visible'' - by which they mean that more should be known about their personal attitude to reform and major policies.

Though anxious at the narrowness of their victory, radicals are nonetheless pleased with some aspects of the Andreyeva affair. They note with relief that the media did not immediately buckle to Ligachev's pressure. And they say counterpressure from intellectuals - in the form of letters to newspapers and resolutions from official bodies - stimulated the fight back.

They also say the main struggle lies ahead: the process of selecting delegates for June's Communist Party conference. Radicals view the conference as a potential watershed in the reform program.

However, they are worried that local party leaders - often, they say, the most active opponents of change - will dominate the nomination process, thus blunting the conference's impact.