It might not happen at all. But if it does, it will pluck the chords of race, resonating differently among blacks and whites. Its revelations will be sifted on Capitol Hill, perhaps shaping laws. The world will take note of it, surely with disapproval. Reputations will rise and fall from it. A city's history will change with it.

Such are the stakes of federal case 90-0068, the United States of America v. Marion S. Barry Jr.

Tomorrow, in the 12th year of his mayoralty and more than seven years after his name was first linked publicly with cocaine, Barry is scheduled to walk into Courtroom 2 of the U.S. District Court building on Constitution Avenue to begin his trial on 14 charges that he used cocaine, conspired to use it and lied about using it. {Little progress reported in plea negotiations, Page A18.}

In recent days, reports have persisted that Barry and federal prosecutors have discussed the possibility that the mayor would plead guilty to some charges and thereby avoid his day in court and, possibly, avoid the airing of a government videotape made as he allegedly inhaled crack cocaine on Jan. 18 at the Vista Hotel.

So distasteful do some find the looming spectacle -- the mayor of America's capital in the dock, accused of being infected by the national drug epidemic rather than helping to cure it -- that they say they hope the two sides do, indeed, find common ground for a plea bargain.

That would, they say, minimize the daily humiliation of Barry, a man who instilled pride in many and who rode from society's fringes to bask at its center. It also would, say others, avoid the humiliation of the District of Columbia, a city whose image already has been sullied by murders, drugs and jokes on national television.

"My biggest fear is there will be a parade of witnesses in court testifying in sordid, gory details of what they did with the mayor," said Kevin Chavous, a lawyer who is black. "If that happens, it would hurt the city, it would hurt the mayor. A plea bargain, without jail time, is something that I could accept."

Either way -- trial or plea bargain -- what is about to unfold will be the culmination of a municipal ordeal that began in March 1983 with the revelation that unsubstantiated allegations had been made to D.C. police that Barry had used cocaine at a bar called "This Is It?"

As the city's drug problems mounted, so did allegations that Barry had one too. It was a procession of rumors, denials and headlines, topped by an event heard around the globe: his arrest during a federal sting operation in which a former girlfriend enticed him to her room at the Vista.

After all that, some say, the trial is something concrete and clarifying, at last. "All the innuendoes, all the other kinds of allegations, are going to come down to a small courtroom with 12 people," said Bob King, a longtime Barry supporter. "I'm happy it's where it should be."

But other analysts said they fear the trial will settle little, because so many residents long ago made up their minds about Barry and his case. Still, a trial will touch many segments of the city and many aspects of its life, from race relations to its electoral landscape to its standing on Capitol Hill to its image in the world.

For blacks, the trial triggers a landslide of tumbling emotions. According to polls and interviews with residents, academics and officials, the trial is, for a minority of blacks, solid proof of a conspiracy by white prosecutors to destroy black leaders, an argument Barry himself has made. Angered by what they see as the government's racially fired zeal and still deeply committed to him, they want to see Barry acquitted and probably would be disappointed by a plea bargain.

Frances Murphy, editor of the Washington Afro-American, said the trial would expose to the world how America has two standards of justice, one for whites and one for blacks, and raise the question, "Are we really a true democracy?"

But other blacks, perhaps a majority, seem far more torn. They are unhappy about Barry's conduct and no longer eager to see him as mayor, but bothered by the government's conduct, cognizant of Barry's accomplishments and appalled that a trial might send him to jail. They would like to see him acquitted or plead guilty without being jailed, and then fade away.

"Most people are appreciative of the role he has played in the civil rights movement and in the history of the District of Columbia," said Ron Walters, a professor of political science at Howard University. "They know he came up from the street all the way through the system, and most blacks are unwilling to throw all that away . . . . They want him to disappear, but they don't want to see him crucified."

Whites appear to have no such strong investment. "The majority of whites are just plain annoyed and angry and just want this guy to go," said D.C. Council member Jim Nathanson (D-Ward 3), who is white. Although many whites once supported Barry, polls indicate that almost none do now, and more than a few want a full trial, not a plea bargain.

"There is one camp that is disturbingly large that approaches this with a kind of glee," said Steven Sieverts, a local health-care official, who is white.

The racial divide is so great that some analysts suggested the trial could raise tensions, particularly because no verdict could satisfy everyone. "My fear is the increasing polarization that exists . . . and I hope and pray this trial doesn't exacerbate it," said R. Robert Linowes, a District and Montgomery County zoning lawyer.

Yet others said that while whites probably feel less compassion toward Barry, most are as saddened as blacks by what has happened, and these analysts doubt racial temperatures will rise. "They're just as eager for a plea bargain as a lot of other people," said Alvin Thornton, assistant dean of the college of liberal arts at Howard.

Beyond the trial's impact on the races lies the impact on the city as an entity.

There are those who doubt its reputation could suffer any more than it has from waves of murder and drugs. But former U.S. attorney Joseph E. diGenova said he could imagine how a trial could make it worse: "Yeah, show the tape," he said, referring to the Vista videotape.

Some officials seem especially worried by the possibility of testimony that Barry's alleged cocaine use affected city operations or involved city finances or contracts. On Capitol Hill, where the District must win passage of its budgets and where the issue of statehood stirs again, such revelations could fuel sentiments that the District needs to be reined in or scrutinized more. There is, some say, more than a hint of racism behind that.

"It's not just Marion Barry that's on trial," Walters said. "What's on trial here is the District of Columbia government, and by extension black leadership."

There is concern too among businesspeople and others about the worldwide publicity the trial would receive. There are signs that tourism already has slipped because of the District's problems. With the additional notoriety of a trial, the city might be further besmirched as a place to do business and visit, some analysts said.

"I cannot look at the mayor's trial in isolation," said Tom Mack, president of Tourmobile, a bus-tour company. "The image of the city has definitely hurt my business, everyone else's business."

The trial also has enormous significance for a selected group of people: the five major Democratic candidates for mayor. Barry's uncertain legal status has effectively frozen the campaign because the five don't know if Barry will be in the race.

If he is convicted and chooses not to run -- he would not be legally able to run if he is jailed on a felony conviction -- the five others will scramble for his supporters. An acquittal obviously would make him more viable, although there is sharp disagreement over just how politically alive he would be.

At stake in the trial as well is the reputation of U.S. Attorney Jay B. Stephens and his office. Given that many in the black community believe the prosecutors are engaged in a witch hunt, an acquittal might seem further proof that there were no grounds for the Barry pursuit.

Last, the stakes are highest for the defendant.

"Everything rides on it," said King, the Barry supporter. "It is the birth and death of Marion Barry."