Congressional and Reagan administration leaders met yesterday under the shadow of economic crisis to begin discussions about a compromise budget package in which both sides said that every disputed issue, including revenue increases, will be on the table.

President Reagan, without abandoning his oft-stated opposition to tax increases, said he is "willing to look at any proposal" submitted by the Democratic leadership of Congress.

Late in the day Senate Majority Leader Robert C. Byrd (D-W.Va.) and House Speaker Jim Wright (D-Tex.) issued a statement declaring their willingness to participate with the president "in a creative search for additional ways to reduce these staggering deficits." They added, however, that Reagan's "personal

President Reagan's news conference will be broadcast live by the major networks at 8 tonight.

involvement in the process is essential."

The White House had no immediate response. However, an official said White House chief of staff Howard H. Baker Jr. assured congressional leaders in private meetings earlier in the day that he is "confident" Reagan would be willing to meet with them if necessary to strike a deal. Reagan said Tuesday that he is "willing to be a participant."

A senior official said that the White House chief of staff and Treasury Secretary James A. Baker III will report to Reagan today about their conversations with congressional leaders and that the president is expected to comment on these meetings at his news conference at 8 tonight.

The two Bakers, accompanied by chief legislative liaison Will Ball and Office of Management and Budget Director James C. Miller III, held four meetings yesterday with congressional leaders on Capitol Hill. One official said Congress and the administration are anxious to demonstrate that they can take coordinated action to deal with the federal budget deficit in the wake of Monday's record stock market dive. A senior official said there is "apprehension" on both sides that the recovering market could head downward again if negotiations fall apart.

"The negotiation process has started, and that should bring some confidence to the markets," said Senate Minority Leader Robert J. Dole (R-Kan.) after meeting with the administration officials. Byrd said the officials had told them that the White House is serious about substantive talks and did not rule out the possibility of a tax increase, an option that has been pushed by the Democratic leadership.

"They indicated a recognition of the fact we have to be flexible and if we negotiate we can't rule out . . . any options that are available," Byrd said.

But while stressing that he is willing to listen to tax-increase proposals -- a concession Reagan had been unwilling to make before the stock market's deep fall -- the president reiterated his longstanding opposition to tax increases.

"I have not changed my mind about the impact of increased taxes, which does not result in increased revenues," Reagan said on his way into a meeting with Honduran President Jose Azcona. "Historically, tax increases result in reduced revenues, and reduced tax rates result in increased revenues. And that's a point that I would make in any discussions."

Administration officials and congressional leaders said, however, that there are elements of a potential compromise that could reduce the deficit significantly. Congress has been as adamant about not using sales of federal assets to reduce the deficit as Reagan has about tax increases. The indications yesterday were that both items are now open to discussion.

"It might be possible to make a $20 billion to $30 billion dent in the budget by some grand compromise that includes some asset sales, some revenue measures and some cuts in both domestic and defense spending," said one official. "But we haven't yet reached the stage where anybody is talking in those kind of specifics."

One senior official said that the discussions yesterday were "mostly about the size of the table," meaning that they were preliminary and concerned the process of the coming discussions rather the content of a compromise.

Sen. Pete V. Domenici (N.M.), ranking Republican on the Senate Budget Committee, said, "at this point there are no prescriptions or restrictions."

"Everybody might have to take a look at their hole cards again," Dole added.

The administration representatives also met with Wright and House Minority Leader Robert H. Michel (R-Ill.).

Yesterday's flurry of meetings came as lawmakers of both parties jockeyed for political advantage and struggled to interpret what some of them saw as conflicting signals from the White House. These signals started in a statement read to reporters by Reagan Tuesday after his 40-minute meeting with top advisers to discuss measures to reassure Americans shaken by the wild gyrations on Wall Street.

The ambiguity of White House signals on the tax issue produced considerable confusion in Congress, and even some suggestions that the administration was only trying to buy time until financial markets recovered.

"Who knows what it means?" said Sen. John C. Danforth (R-Mo.), a member of the Budget and Finance committees. "It may not mean anything; it may be just a blip."

Added Rep. Byron L. Dorgan (D-N.D.): "Many of us on the Hill are not sure whether it's talk, whether they loaded him with some words and sent him out to say those things, or whether they're really serious about deficit reduction. You never know with this administration."

But Senate Finance Committee Chairman Lloyd Bentsen (D-Tex.) reflected the views of many when he said that the financial upheavals of the past week have produced a "sea change" in the administration, turning Reagan into a "reluctant convert." Nevertheless, Bentsen said, "you're getting mixed signals on the tax side."

"I think Wall Street has gotten his attention when Pennsylvania Avenue couldn't," concluded House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.).

Dole said yesterday's meetings were "the beginning" of joint efforts to lower the deficit and avoid $23 billion in automatic budget cuts that will take place next month absent an agreement between the White House and Congress to cut the deficit by that amount. But when asked what "the plan" was, Dole replied: "The plan is to get the market up."

Wright, meanwhile, used unusually harsh rhetoric in insisting that any summit include the president and in promising that the House would move ahead with plans to bring a $12 billion tax increase bill to the floor next week.

"Not until the president is personally engaged do I expect any real progress on the deficit," Wright said. The speaker said if the president sends his budget chief to negotiate, he would have to meet with the House Budget Committee chairman, and that "if he sends up the vice president, we'll have our majority leader meet with him."

"I'll believe it when {Reagan} sits down and says, 'Okay, I'm willing to face reality,' " Wright said.

Wright also rejected a request from Republican leader Michel to delay action on the tax bill, though Democrats seemed warmer to Michel's suggestion that a working group be appointed to begin talks with administration representatiaves.

Michel and other Republicans also are pushing the idea of an across-the-board budget freeze that would save about $11 billion.

Meanwhile, Democrats prepared to milk the maximum advantage from the financial crisis if Republicans do not cooperate in producing a deficit-reduction package that includes higher taxes.

One member of the Democratic leadership has had thousands of buttons printed up that read "GOP=AWOL," with the acronym AWOL standing for Absent Without Leadership. Staff writers Anne Swardson and David Hoffman contributed to this report.