WITH just a day to go before the opening of the Soviet Union's new parliament, the Congress of People's Deputies, there are increasing signs that maverick political leader Boris Yeltsin plans to challenge Soviet leader Mikhail Gorbachev for the country's presidency. After a big rally Sunday night, staged by some groups calling for radical political and economic reform, one newly elected deputy asked Mr. Yeltsin, ``Do you want to be president?''
Yeltsin, he recalled, demurred. ``I don't want to, but the people want me to,'' he answered.
Some of the same radical deputies who had supported Yeltsin against official attacks during the campaign - and in some cases were elected on his coattails - are beginning to be apprehensive of both his ambitions and his real political platform.
A plenary meeting of the Communist Party Central Committee Monday ``recommended'' Mr. Gorbachev's candidacy for the presidency. Until the March 26 elections, it seemed inevitable that Gorbachev would be the only candidate. But the elections, with their anti-establishment groundswell and Yeltsin's overwhelming victory in Moscow, dramatically changed the political landscape.
There are signs that the party leadership is still trying hard to keep the situation under control. Gorbachev addressed one so-far unpublicized meeting of new deputies on Monday afternoon.
Deputies who attended were reportedly displeased that the Soviet leader apparently tried to present an agenda for the congress: Deputies have said repeatedly that they want to do this themselves when they convene. Other new members of congress complain that the leadership is trying to pack the new standing parliament - the 542-member Supreme Soviet, which will be elected by the 2,250 deputies this week - with little-known or conservative deputies.
During the March electoral campaign, Yeltsin frequently emphasized his near-total agreement with Gorbachev, and stressed that he did not see himself as an alternative to the Soviet leader. But some versions of an interview he gave in November 1988 to regional newspapers indicate that even then he was beginning to undermine Gorbachev's position.
One version quotes Yeltsin as confirming that Gorbachev had built himself a dacha (country residence) in the south. Yeltsin also refused with characteristic ambiguity to comment on reports that Gorbachev had banked fees received from the publication of his writings overseas.
Gorbachev seems indirectly to have been responding to these innuendos in an interview published in the latest issue of the monthly Izvestia TsK (Central Committee News), which reached journalists yesterday.
In the three-page interview, he denied that he or any other family member owned a personal dacha. He said that all the profits from his writings go straight into Communist Party funds or to charity. And he also disclosed his salary - 1,200 rubles ($1,900) a month.
Meanwhile Yeltsin is undoubtedly deriving intense satisfaction from the way his arch-rival, Yegor Ligachev, is fighting for his political reputation. At Monday's plenum, Mr. Ligachev took the extremely unusual step of issuing a personal and lonely sounding statement concerning corruption charges leveled against him by a former state investigator, who was elected to the congress by a wide margin in a second round of elections held last week. The charges, he claimed, were a ``provocation.''
Yeltsin is by no means a passive bystander in the onslaught against Ligachev. Telman Gdlyan, a former chief investigator and Ligachev's main accuser, is one of Yeltsin's closest political allies. Gdlyan has come under intense official criticism because of his accusations, and a defense committee has been formed by his sympathizers. The defense committee is headed by Lev Shemayev, Yeltsin's unofficial campaign manager in the congressional elections.