President Obama emerged from an Oval Office meeting with Congressional leaders on Wednesday night with no breakthrough on the budget stalemate, but he said the 90-minute discussion had helped to "narrow the issues" that are outstanding.

In brief remarks to reporters at the White House, Mr. Obama made it clear that he and Vice President Joseph R. Biden Jr. had not been able to bridge the divide between House Speaker John A. Boehner, the top Republican, and Senator Harry Reid of Nevada, the majority leader. Mr. Obama said the two sides would "work through the night" to try and reach a deal that could avert a shutdown of the federal government on Saturday, when the authority to spend money expires.

"In the morning, I will check in with the respective staffs," Mr. Obama said. "If we haven't made progress we are going to go at it again."

Mr. Reid and Mr. Boehner appeared briefly together in front of reporters after Mr. Obama's remarks. Both men described the nighttime conversation as "honest" but said a deal between them remained elusive.

"I have confidence that we can get this done," Mr. Reid said. "We are not there yet."

Mr. Boehner said that "I do think we made some progress." But he said he wanted to make it clear that "there is no agreement on a number and there is no agreement on the policy side."

The fact that the two Congressional leaders appeared together - even if only briefly - suggested that the meeting with Mr. Obama had managed to dispel some of the rancor that has characterized the public debate over the past several weeks. But the president and the lawmakers made it clear that there remain divisive issues that separate the parties as they seek to avoid a government shutdown.

As he did earlier in the day, Mr. Obama said a shutdown would impact real people and must be avoided.

"It would be inexcusable, given the relatively narrow differences, when it comes to numbers, between the two parties that we cant get this done," Mr. Obama said.

The meeting, called Wednesday afternoon by Mr. Obama, underscored the drama in the nation's capital as the White House and Republican lawmakers on Capitol Hill spent the day pointing fingers at each other in advance of a possible government shutdown on Saturday. The government's authority to spend money runs out at midnight on Friday night.

The meeting was called after a day of pointed sparring between Democrats and Republicans, with Mr. Boehner accusing Mr. Obama of failing to lead in the budget negotiations, while the president said Republicans had injected politics into the budget negotiations.

And with little solid progress in resolving the fight, House Republicans moved ahead with a one-week budget extension, including more cuts, that the White House has already rejected. Republicans hoped that passage of the measure would put pressure on Democrats in the Senate and on Mr. Obama to make concessions on spending cuts and policy changes that Republicans want in exchange for a final budget deal. But administration officials warned that a shutdown would lead to the layoffs of as many as 800,000 federal employees and hobble agencies that offer help to small businesses and homeowners.

Late Wednesday afternoon, Mr. Reid took to the Senate floor to excoriate Republicans for not agreeing to compromise budget proposals by the Democrats.

Mr. Reid accused Republicans of seeking a "shortcut around doing our jobs" by proposing another one-week, stop-gap funding measure to keep the government operating.

The White House meeting came after a group of 16 Democratic senators sent a letter on Wednesday to Mr. Boehner, urging him to avoid a government shutdown because it would distract from the need to confront the nation's longer-term fiscal challenges.

"A government shutdown at this time will only serve as a counterproductive attack on our economic recovery," the senators said in the letter. "Economists note that a suspension of services would have a measurably detrimental impact on our economic output, while business leaders warn about a shutdown's impact on confidence in the U.S. economic recovery. A setback of this nature would prevent the growth we need to tangibly address our long-term fiscal imbalances."

The Obama administration's efforts to spell out in detail the effects of a government shutdown appeared meant to put pressure on lawmakers to reach a deal by highlighting the scope of the pain Americans would feel if the government stopped operating, even for a brief period of time.

Administration officials, who declined to be quoted by name, focused on the economic consequences of a shutdown. But they also said that national parks would close, the Smithsonian would stop operating and the Cherry Blossom Parade in Washington, an annual tradition, would be postponed or canceled.

In 1995, when the government shut down for several weeks, federal workers who were deemed essential stayed at work but about 800,000 federal employees who were deemed nonessential were furloughed. Officials estimated on Wednesday that a similar number would be furloughed this time.

The Internet was just beginning to catch on with the public in 1995, but today, the federal government has a large online presence, most of which would be idled in a shutdown. "Only those Web sites that are part of these essential activities will continue to operate," a senior official told reporters.

In the event of a shutdown, Medicare payments would continue, officials said, because the program's money comes from a trust fund that is not affected by the annual budget process. But the Environmental Protection Agency would stop issuing permits, which would slow construction of transportation and other infrastructure projects, they said.

Military employees would not be told to stop working, and would continue to earn their salaries during a shutdown, officials said. But they would not actually receive their paychecks until a new budget is in place. Civilian employees at the Defense Department would be subject to the same determination of need as other federal employees.

"A significant number of D.O.D. civilian employees, unfortunately, would be furloughed," the official said.