Mayor Marion Barry's long-awaited financial salvation plan for the city may be as important to his political future as it is to Washington's fiscal health.

When he delivers the proposals tomorrow night, Barry will be walking a political tightrope between constituencies whose conflicting needs he seldom has been able to reconcile.

District business leaders, who were initially cool to Barry, have applauded his early cuts in what they see as a bloated bureaucracy. They want to hear more of the same when Barry speaks on television tommorrow night.

But labor groups -- including the few that endorsed Barry in 1978 -- are wondering when the mayor will reward their support by saving their jobs and services on which their members depend.

Neighborhood, church and civic leaders, including many who were lukewarm to Barry during his campaign, have cheered his strident criticism of Congress as the villain of the city's current fiscal horrors. They too, would like to hear more such talk.

But, finger-pointing toward Capitol Hill has angered many members of Congress, and it is they whom Barry will have to depend on for help in curing the city's worsening financial crisis.

Tomorrow night's speech will climax months of grappling in Barry's young, narrowly based and image-conscious administration over how to solve the worst financial crisis in the city's history.

Some observers believe that what Barry says tomorrow night will not only shape the political future of the 44-year-old career politician, but also have significant impact on the future of home rule in the nation's capital. But Barry does not think that.

"My speech on Monday will not be a political speech," he insisted yesterday, as he left the District Building where he was reworking the address.

"Once I make the speech and do other kinds of actions, there are political concerns in terms of how constituencies view me," he acknowledged.

But, he said, "I don't think this budget crisis and the way I handle it is an absolute test of my administration. And I reject absolutely the notion that this is a test of home rule. Whether or not we solve our budget problems should have no impact on our ability to govern ourselves."

The Rev. Robert L. Pruitt, pastor of the influential, largely black congregation at Metropolitan African Methodist Espiscopal Church downtown, however, was typical of more than a dozen key persons interviewed in his assessment of what is at stake for Barry.

"I think this speech will determine his political future," Pruitt said. "What we need now is the Roosevelt approach, someone to say this is what needs to be done and then to do it.

"It's not the mayor's fault that he came along in bad times. But great men are born in bad times. We'll see now whether the mayor is great or whether he's a pygmy."

The budget crisis has been a traumatic experience for the city. Police officers have taken to the streets to distribute leaflets attacking the cut-backs. Firefighters, senior citizens and community activists have come to the District Building to protest, with Barry, himself a former activist, at one point telling a group of critics to go to hell.

Health and recreation centers have been closed. City workers, once confident that such a day would never come, have received pink slips.

Barry aides said last week that the mayor's rescue plan -- the fourth his administration proposed since he discovered the financial crisis in January -- will call for painful reductions in city services and personnel, extensive congressional aid, more support from the White House and some borrowed funds. c

In deciding, what will be cut and (what will not), and who will be taxed (and who will not), Barry will have to choose between various political constituencies who have had different views of his handling of the crisis so far.

Business leaders say they are giving Barry at least conditional support in his efforts to solve the crisis. "I think he's done very well; I really do," said Ralph Frey, president of the Greater Washington Board of Trade.

The business leaders, who often felt shut out of the administration in the past, applaud a series of budget briefings Barry has given them in recent months, and they praise his efforts to publicize the extent of the crisis. But most loudly, they support Barry's efforts to trim the city's 43,000-member workforce. More than 2,000 layoffs have been proposed to date.

"People think he's pulling together a lot of good things with his job reductions," said one business leader who asked not to be identified. "I think he's made a lot of inroads . . . with doubters, business people who weren't sure about him when he came into office."

But the source said he would be watching the speech closely for "vacillation" on the workforce reductions, like Barry's earlier announcement that he would lay off 250 workers in the D.C. Department of Corrections and his eventual decision to suspend only 76.

"The attitude seems to be that he is trying," said attorney R. Robert Linowes, a politically active lawyer and former president of the Greater Washington Board of Trade. "He's come a long way since the election. People are concerned and very sympathetic."

On the other hand, organized labor has strongly opposed the job reductions, and some leaders privately complain that Barry is antilabor.

"From what I understand, labor is getting very restless in this town," said Larry Melton, vice president of Local 442 of the International Brotherhood of Police Officers, which supported Barry in the 1978 election. The union faces the loss of 204 police officers by the end of this year.

"He has to do something to bring the labor movement back into a decent relationship with him," Melton said. "Right now, the relationship is pretty low."

Melton and other leaders complain that Barry does not inform them of actions he plans to take -- like his decision, announced last week, to support no pay raises for city workers next year. "The first I heard about it was when a reporter called me," Melton said.

Washington Teachers Union President William H. Simons said layoff notices have been sent so far to around 500 teachers. "At this point, I don't know if I could sell him again to the membership or not," Simons said.

Business and labor agree on only two points -- that it has taken too long for Barry to demonstrate he is in control of the budget crisis, and that he must now set forth long-range goals so everyone knows what to expect.

Everett Scott, president of the D.C. Federation of Civic Associations, said he believes the central issue is the size of the federal payment, which Congress pays to the District government each year, primarily to compensate for the loss of revenues from tax-exempt land owned by the federal government.

Barry has used every opportunity to criticize Congress for not approving a large enough payment, maintaining that the city should get nearly twice as much as the $300 million maximum now authorized. But some business leaders consider that unrealistic.

And Capitol Hill sources say key congressman have already been angered by Barry's harping on the federal payment issue. "On the one hand, he's blaming Congress and making the situation sound worse than it really is," said one source.

"While on the other hand he's coming up here for money. I frankly don't think anything's happened to change people's attitudes up here."

Barry's speech will have to in some way address all these political concerns, while at the same time charting a course for the city out of a maze of frightening numbers -- a budget deficit for the current year of up to $170 million, an accumulated deficit of $284 million, a long-range problem of expenditures outpacing revenues.

Barry spent most of yesterday in his high-ceilinged office reviewing the speech. Alan F. Grip, his spokesman, said videotape equipment would be set up in Barry's office today so that if he wants, the mayor can practice.

The speech will be carried at 7:30 p.m. tomorrow on the city's three major commercial television stations -- WRC (4), WJLA (7) and WDVM (9) -- as well on a number of radio stations. Elaborate arrangements have been made to brief the City Council and the press on what Grip has called "certainly the most important speech" Barry has given as mayor.

Emerging from the District Building yesterday afternoon in shirt-sleeves clutching a heavily marked draft copy of the speech, Barry said he would "retain some basic commitments."

"We cannot abandon our commitment to the poor," he said. "We have a commitment to protect our streets. These are things we've got to stick to.

"The majority of people I talk to don't want any new tax increases," Barry said. "But these are the same people who say don't close my recreation center. I have to make some very unpopular, agonizing decisions."

Barry said the objections of labor groups to his budget-slashing proposals were natural. "Any labor leader who doesn't oppose layoffs and attrition is not reflective of his constituency," he said.

Barry took credit for bringing the financial crisis to light -- though it first surfaced in January when an internal memo leaked to the press -- and said he had decided on the televised speech because so much attention is focused on the city's plight.

"The budget crisis goes beyond this administration in terms of significance," he said. "It goes beyond me as mayor. It is of great significance to our nation's capital."

Said one City Council member who asked not to be identified: "The speech is very important, terribly important because he's built it up to such a big thing. He's really got to shine."