The 80 businessmen and professionals who gathered one recent evening in the Cleveland Park home of lawyer Max M. Kampelman seemed easy pickings for Patricia Roberts Harris, the former Carter administration official and early leader in the Democratic race for mayor of the District of Columbia.

Harris, 58, a feisty, matronly looking woman with frosted golden hair, skillfully conjured up the memory of Sen. Hubert Humphrey while recounting her civil rights record.

She promised to eliminate red tape that has frustrated local businessmen; to put an end to the "adversarial" relationship between the city and Congress; and, most important to some of the well-heeled liberals gathered that evening, to bring a touch of class and administrative skill to D.C. government that Harris claims has been sadly lacking under Mayor Marion Barry.

But even as many of the guests nodded and applauded approvingly and promised to offer her financial support, others wondered whether Harris was as strong a leader as she claimed, and whether she has the right temperament for the job.

"Is she arrogant?" Charles E. Smith, a major Washington builder, asked Kampelman as they stood in the center of Kampelman's spacious, book-lined living room.

"I've never found her to be that," replied Kampelman, a member of Harris' former law firm. "Tough, yes; but not arrogant."

Smith said later that he was impressed with Harris, but curious about stories going around that she has a prickly personality and had been difficult to deal with when she was secretary of Housing and Urban Development (HUD) and Health, Education and Welfare (HEW).

Harris is sensitive to the criticism, but insists that it is unfair and has been overblown by her opponents.

"If I were male and white, I would be known as the very firm, strong manager who communicates clearly and precisely," Harris said in a recent interview. "The fact that I am what others would call an uppity black female means that what is positive in a white male is seen as off-putting and arrogant in me."

The concern about Harris' personality and record underscores a significant change in the complexity of the mayor's race since Harris formally declared her candidacy April 3.

She stirred up considerable interest in Democratic circles at the time, but nonetheless was viewed by many as one of a handful of Democratic challengers waging an uphill battle to unseat the incumbent. Harris portrayed herself as the underdog and predicted that Barry's "sorry performance in office" would be the central campaign issue.

But now all that has changed. Harris is ahead of Barry in the early polls--leading him in one survey by 11 percentage points--and assumed the enviable but perilous role of front-runner and a prime target for the other candidates.

She is labeled an outsider in city politics, and criticized for missing 11 of the 20 major candidates' forums held since April. She is pressed for specifics when she takes stands on local issues and her record in the federal government is occasionally challenged.

At a recent forum at Woodrow Wilson High School near Tenley Circle NW, for instance, Barry said Harris "has never balanced a budget" as he has done. He also told a reporter that many of the programs Harris administered at HUD would have functioned smoothly "even if Mickey Mouse had been secretary."

"Harris has been out of town too much at IBM board meetings and on the Eastern shuttle," D.C. Council member and Democratic candidate Betty Ann Kane said this week. "It's time she got off the shuttle and on the streets of Washington."

Harris contends that many of the forums she missed were a waste of time because they didn't offer candidates enough time to explain their views.

"Three minutes, as one forum offered me, to tell what I would do as mayor of the District of Columbia is very troubling to me," Harris said. "It becomes theater. It does not become dialogue."

Harris generally has performed better in smaller, less formal settings, where she appears more at ease and playful, than at large, formal meetings with the other candidates, where she often appears rigid and humorless.

At a May 25 meeting, she gamely sparred with 90 members of the Gay Activist Alliance and received enthusiastic applause despite her refusal to disavow the support of Douglas E. Moore, a former at-large council member whom gay rights advocates consider an ardent foe. "I do believe in redemptive possibility," Harris quipped.

But at a much larger forum sponsored by the American Federation of Government Employees and attended by 500 people and most of the Democratic candidates, Harris seemed like a stick in the mud.

When council member and fellow candidate John Ray joked that "there isn't a dime's worth of difference" among Barry's challengers, everyone laughed except Harris, who sat grim-faced.

Harris is philosophical about most of the attacks from her opponents, except for the criticism that she has lost touch with the city--criticism that she says totally overlooks the fact that she has lived in Washington for most of the past four decades and been involved in a wide range of civil rights, legal, governmental and political activities.

"I have always been locally involved," she declared.

Harris' early campaign strategy has been to stress her broad civic and government service and her vision for the city's future without getting into the details of what she would do if elected mayor, while waiting for her staff to develop a series of campaign position papers.

But increasingly she is being pressed by prospective supporters to spell out her plans.

When a member of the Foggy Bottom Civic Association asked Harris at a May 24 meeting to explain in detail how she intended to combat crime, increase housing for low- and middle-income families and achieve other goals, Harris spoke of the need to "maximize" resources and improve government efficiency.

"I would have liked more specifics," the questioner later told a reporter. "I would have liked some more substantial responses."

Still, Harris continues to generate enthusiasm with her attacks on Barry's administration and her call for imaginative, firm leadership. "I want to be your mayor because I think we have lost the vision of greatness we once had," Harris said at the Ward 3 forum this week. "We have reached the point where we envy Baltimore because it has a vision of itself that we don't."

Harris criticized Barry for sharply reducing spending for recreation programs and for continually battling with the D.C. school board over spending for education. She promises to spend more money in both those areas if she's elected mayor.

While her aides are jubilant over Harris' fast start, they feel that she is not as far ahead of Barry as the early polls suggest.

They respect Barry as a shrewd, formidable politician, skilled at exploiting his incumbency and mobilizing a dedicated political organization that has backed him since 1968.

Harris' advisers say she enjoys unusually high name recognition because of her national reputation as an administrator. Moreover, her support extends far beyond her "natural constituency" among middle- and upper-income blacks, according to the aides.

"Any U.S. senator would be satisfied he had that kind of substantive recognition," said Peter D. Hart, a prominent political consultant and pollster working for the Harris campaign. "The more this contest revolves around professional ability, the stronger Pat Harris will be in this election."

Sharon Pratt Dixon, Harris' campaign director and top political adviser, said the backbone of Harris' support is in Wards 4, 5, and 7, in Northwest and Northeast Washington, and Ward 8, southeast of the Anacostia River.

"All these wards are variations on the theme of working-class blacks," she said. "This is a town that understands institutions and respects Congress. Although they faulted former mayor Walter E. Washington in some respects, they respected him for his relations with Congress."

Harris also expects to do very well in Ward 3, a predominantly white, upper-middle-class area west of Rock Creek Park, and in parts of Ward 6, in the Capitol Hill area. The early polls showed Harris running far ahead of Barry among the city's white voters, and Barry's camp has all but conceded Ward 3, which Barry carried in 1978, to Harris and Kane.

Harris has been unable to recruit a campaign manager with broad experience in D.C. politics. She eventually hired Arthur Murphy, an expert on voter-turnout techniques who served as Virginia Gov. Charles S. Robb's deputy campaign manager last fall.

Murphy described his role chiefly as that of a campaign "technician" and he usually defers to a policy group headed by Dixon, with Washington lawyer James L. Hudson as the chief adviser on political operations. Harris also has hired a Philadelphia firm called The Campaign Group for political advice.

Aides say her campaign has raised about $300,000 of the $500,000 initially sought to help finance a midsummer television and radio advertising campaign and to pay for polling. By comparison, Barry has raised in excess of $600,000.

Her aides insist that the arrogance issue, at most, has caused Harris minor problems in the early going and that their campaign is continuing to pick up steam.

"They Harris opponents spread stories that Pat doesn't relate to the people," said Michael Wheeler, another cochairman of the Harris campaign who drives Harris to many events. "But it's more that people are in awe to be in her presence . . . They say the lady is a lady of class. She's got something to offer and it's killing Marion. He knows it."