Vast crowds poured onto the streets of Soviet cities to back populist politician Boris Yeltsin and call for the resignation of President Mikhail Gorbachev, his arch rival. About 200,000 people turned out Sunday in Moscow, where demonstrators chanted, ``Gorbachev get out.''
Tens of thousands gathered in other cities and in other Soviet republics to support Mr. Yeltsin, who is a folk hero to many Russians weary of shortages of goods.
The Moscow demonstrators listened to reformist politicians denounce next week's referendum on preserving the Soviet Union and the latest draft of a union treaty on new links between Moscow and the country's 15 republics.
It was one of the biggest protests since Mr. Gorbachev launched his perestroika reforms in 1985.
The protests raised the stakes even further in months of the Kremlin's political battle with Yeltsin, president of the Russian Federation, the biggest republic.
But Soviet television, run by a Gorbachev loyalist, devoted 20 minutes of the evening news to condemnations of the rally and of a speech the day before in which Yeltsin said, ``Let's declare war on the leadership of the country, which has led us into a quagmire.''
Anatoly Lukyanov, speaker of the national parliament, which is dominated by Communists hostile to Yeltsin, promised a debate after Yeltsin's speech on Saturday. He urged reformists to combine against Gorbachev, insisting that Russia was not ready to sign the union treaty.
Yeltsin also faces a revolt from hard-liners within his own Russian parliament, when it reconvenes later this month.
Participants at Sunday's rally in Moscow accused the Communist Party of trying to perpetuate its hold on power with the referendum, which asks voters whether they favor keeping the country as a ``union of sovereign equal republics.''
``We are being asked: Do we or do we not trust the leadership of the country?'' Moscow's radical Mayor Gavril Popov told the crowd.
``No!'' the demonstrators roared back.