The negotiations are an attempt to build a political consensus that might save Russia from economic collapse, after a steep plunge in the value of the rouble and near-paralysis in financial markets during the past week.

Chernomyrdin said on Saturday he was hopeful a deal between government, Yeltsin and the Communist-dominated lower house of parliament, badly needed for Chernomyrdin's formal confirmation in the state Duma, or lower house, could be reached by the end of Sunday.

But Chernomyrdin's main opponent, Communist Party chief Gennady Zyuganov, demanded that Duma voting on the new premier be postponed from Monday to Tuesday or even later in a move which could leave Yeltsin without a full prime minister during a crucial summit meeting with US president Bill Clinton this week. Chernomyrdin, recalled by Yeltsin a week ago after five months of political disgrace, has already agreed with parliament on a draft economic strategy which provides for more state control of the economy.

But he ruled out on Saturday any return to the Soviet past and reiterated his commitment to market reforms, asking the West to understand the realities of Russia's desperate economic plight.

On Friday Chernomyrdin formed a group of senior reformers headed by acting deputy prime minister Boris Fyodorov, setting them the task of preparing urgent anti-crisis measures.

In another possible sign of his determination to stick to the reform path, Argentinian media reported that Chernomyrdin had asked Domingo Cavallo, the man who eradicated four-digit inflation from the Latin American country, to advise his cabinet.

Russian officials were not immediately available to confirm the reports.Washington sounded cautiously optimistic about Chernomyrdin's reassurances.

``It's hard to comment at this point until they have a government, they formally have their economic team and they formally lay out their economic programme, but certainly it is encouraging,'' White House spokesman PJ Crowley said.

Chernomyrdin and Yeltsin's chief of staff Valentin Yumashev,who spend four hours late on Saturday bargaining with parliament, are expected to return to the gloomy Duma headquarters overlooking the Kremlin for more talks at 0630 GMT.

The draft agreement provides for redrawing the constitution to give parliament more control over the government but also approves the nomination of Chernomyrdin as prime minister and his deputies and some key ministers.

The initial copy of the draft also contains provisions offering Yeltsin legal protection from prosecution and a generous pension on retirement if he decides to quit early.

But Yeltsin said in a television interview on Friday that he will serve his full term until 2000 and his aides informed the parliament that the president did not need a safety net, asking the legislature to drop the latter provisions from the draft.

Chernomyrdin and the Duma's Communist speaker Gennady Seleznyov looked optimistic when they talked to reporters after the Saturday's round of talks.``The document is about to be ready,'' Seleznyov said. ``There are few clauses left to agree.''

``For the first time we are about to strike a joint document on ways to handle Russia's problems,'' Chernomyrdin said. ``I think the document will be presented to president Boris Yeltsin as early as this Sunday.''

Yeltsin is due to approve and sign the document which later will be formally confirmed by resolutions of the Duma and the federation council, the upper house.

But Zyuganov, whose party heads a left-wing coalition dominating the Duma, poured cold water on Chernomyrdin's and Seleznyov's optimism.

``The debates are pretty tense,'' he told reporters after Saturday's talks. ``They are a collision between forces who solely want the premier confirmed and those who understand that the cabinet should be protected from Yeltsin's arbitrary rule.''

This demand could overshadow Clinton's visit to Russia, which starts on Tuesday. The US president will seek more clarity on Russia's plans in tackling economic crisis and his impressions might be crucial for future relations between Moscow and the West.