House and Senate negotiators yesterday embarked on the mission of settling the details of a deficit-reduction plan as President Bush extended the deadline through Wednesday by signing a stopgap spending bill.

Conferees planned to work through the weekend to try to reconcile two widely divergent packages of tax increases and benefit-program cuts into one measure acceptable to majorities of the House and Senate, to Bush and, with Election Day barely two weeks away, to the American voters.

As bargainers met on Capitol Hill, the Senate gave final congressional approval to a stopgap, omnibus spending bill that would keep the federal government running at full force through Wednesday. The House had approved the measure Thursday night, 379 to 37.

Earlier this week, Bush vowed not to accept another short-term funding bill if Congress had not enacted a deficit-cutting plan by last night, when temporary spending authority was set to expire. But yesterday, Bush signed the measure, averting the second government shutdown in three weeks.

"What I'm trying to do in the last . . . few hours of this Congress is say, 'Look, let's put the people's business first,' " Bush said yesterday at the White House. "Let's lay aside this political rhetoric and get a job done that should have been done long ago." Bush spent four days this week on the campaign trail lashing out at congressional Democrats.

Later, the president went to the Capitol to get a progress report from congressional leaders. "I'm here to discuss . . . what we can do at the White House to help move the process forward," Bush told reporters. "I'm really just here to say . . . we agree to finish the job."

During the meeting, Bush pressed lawmakers to see if they could finish work on the five-year, $500 billion deficit-reduction plan by last night, participants said. Senate Finance Committee Chairman Lloyd Bentsen (D-Tex.) replied that Sunday was more likely. But even that target is optimistic, observers said.

The difficulty of the task facing the congressional bargainers is reflected by the differing natures of the House and Senate votes narrowly approving their significantly different deficit-cutting packages.

Early yesterday morning, the Senate passed its compromise measure on a 54 to 46 vote with a slim majority of both Republicans and Democrats supporting the bill. Tuesday night in the House, on the other hand, only 10 Republicans joined 217 Democrats to narrowly pass, 227 to 203, the House version, which had been crafted by Democrats.

Three major issues face the lawmakers: how much savings to achieve from Medicare, how much to raise the federal gasoline tax and how to target the wealthy for higher taxes.

Bargainers yesterday made little progress on these matters. One administration aide said early yesterday that reaching a compromise acceptable to both chambers and the administration would be "nearly impossible."

Many Senate Democrats want to move toward the House package, which targets tax increases at the wealthy, contains a smaller savings in the Medicare program than the Senate measure and would not raise the 9-cents-a-gallon federal gasoline tax, as the Senate bill would. But doing that would threaten to lose Republican support in the Senate.

"We have very little wiggle room," said Senate Minority Leader Robert J. Dole (R-Kan.), one of the tax negotiators. "If you move too far in one direction, you lose 10 Republicans, and the bill is dead. If you move too far in the other direction, you lose 10 Democrats, and the bill is dead."

But moving too far toward the Senate package, which relies heavily on higher excise taxes, would imperil the measure in the House. Given the current state of partisan strife in that body, "We're going to have to come up with a package that commands a large number of Democratic votes," said House Majority Leader Richard A. Gephardt (D-Mo.).

"This is all a balancing act," said Rep. Lawrence J. Smith (D-Fla.). "Nobody knows where the lever is."

Finding the political and fiscal balance between the two measures is up to 53 senators and 51 members of the House who are members of the House-Senate conference committee. It is a formidable task. The Senate bill alone is hundreds of pages long, stands six inches high and weighs 13 pounds.

The full 104-member conference probably will not meet until the end of the process, if at all. Instead, nearly two dozen groups are meeting to work on various provisions of the massive legislation, ranging from taxes and Medicare to farm subsidies and fees for weather forecasts.

Lawmakers yesterday agreed on many of the less controversial issues, including $1.7 billion in cuts in student loan programs over five years, half to come from putting a cap on schools with high default rates. House negotiators agreed to drop criminal penalties and floors on fines for occupational safety violations.

Other meetings lagged. At a session on the long-stalled issue of child care, House Education and Labor Committee Chairman Augustus F. Hawkins (D-Calif.) objected to a Senate package.

He asked if the Senate members had come to negotiate or "is this take it or leave it. If it is the latter, then we're just wasting time. I'm ready to leave." Sen. Orrin G. Hatch (R-Utah) urged Hawkins to accept the measure, calling it "a monumental achievement" to get the administration this far. The meeting adjourned until today.

Much of the real negotiating is done by a handful of key lawmakers. For instance, 14 lawmakers are formally assigned the task of settling the details of the tax component. But the real decisions are likely to be made by Bentsen and House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.).

Although administration officials have no formal role in the process, their views are being made known.

Yesterday, for instance, Treasury Secretary Nicholas F. Brady and Office of Management and Budget Director Richard G. Darman were on the Hill for what Darman said were "private meetings," which just happened to be in the anteroom of the House Ways and Means Committee hearing room as the tax negotiators held their first meeting there.

Staff writers Dan Balz and Steven Mufson contributed to this report.