When Barbara Mikulski decided in 1971 to challenge the old-line Democratic organizations in East Baltimore and run for the City Council, she began canvassing her neighborhood, emphasizing her work as a social worker and community activist who had blocked construction of an unpopular highway.

Most people, however, were more interested in doughnuts.

"I would knock on doors and people would say, 'Are you any relation to Mikulski's Bakery?' " said Mikulski, who promptly responded that the bakery was owned by her grandmother. "People would say: 'Listen kid, if you're half as nice as your grandmother, and half as good as your doughnuts, you'll be okay.' "

It was a lesson for Mikulski in the art of politics, Baltimore style, where friendships and family loyalties run generations deep and often are critical to political success in the city's close-knit ethnic neighborhoods. She learned the lesson quickly. Soon she was stationing herself under the Mikulski Bakery sign each workday at quitting time and every Sunday as church let out, handing out leaflets to the people streaming past on their way to buy doughnuts.

She won the City Council race, running as the "local girl" taking on the "big boys." But it was a tough survival course in the male-dominated political world of East Baltimore. In a community where women were expected to find husbands and raise children, Mikulski was viewed as a political outsider, and she had to fight bitter battles -- and stereotypes -- to work her way up through the city government to the House of Representatives.

Now, after five terms on Capitol Hill, the self-proclaimed advocate of women, children, the elderly and labor again is the outsider trying to break in -- this time into the staid, predominantly white and male world of the U.S. Senate, where no Democratic woman has been elected in her own right.

Mikulski, 49, is small and stocky, wears glasses, and has curly, close-cropped hair. She speaks in short, emphatic phrases, punching the air to punctuate her thoughts. Her 4-foot-11 frame seems to be in perpetual motion as she winks, jabs an elbow, marches around determinedly or bursts into laughter at her own one-liners.

Although few would have predicted it a year ago, statewide polls indicate that the tough-talking representative is leading her two major rivals -- Gov. Harry Hughes and Rep. Michael D. Barnes -- in the Democratic primary campaign for the seat of retiring Republican Sen. Charles McC. Mathias Jr.

But some prominent Democrats in Maryland, including some of Mikulski's critics, say privately that her showing in the Sept. 9 primary may boil down to whether voters want someone more conventional, more polished, more "senatorial."

Mikulski has heard that sort of talk, and she has an answer for it. "There's an implied bigotry there, that only a certain kind of person can aspire to public office in this country," she said. "I think a lot of Americans are always told -- whether they're black or white, whether they're female -- they're told that they don't look the part. It's one of the oldest code words that has been used . . . . And I think Marylanders just don't buy that."

Mikulski acknowledges that she is not the "typical" Senate candidate, and she mixes bravado and earthy humor to try to turn her homey qualities to her own favor. She holds "Bowling for Barb" and "Bingo for Barb" fund-raisers, jokes about her diets and says that she has been mistaken for "that sex lady," Dr. Ruth Westheimer, who has a popular column and radio show about sex.

But friends say her humor does not mask the frustration and strain of past battles. She has a well-known temper and, in the past, has yelled in high decibels at staff members, according to former aides.

"She's not part of a big law firm or big business," said Robert Embry, Baltimore school board president and former state and federal housing official, who has known her since 1971. "I think there is some resentment against people who have everything handed to them," motivated partly "by being a woman and Polish and small and not being physically the image of success in America."

Mikulski is fierce on the subject. "I announced my [City Council] candidacy [in 1971] and everybody laughed. They said . . .if you're a woman, you could not win in an ethnic, hard-hat district . . . . I defied the odds then, as I have all my life," she said in one campaign speech, jabbing the air with her fist, furrowing her brow and shaking her head defiantly.

Mikulski grew up in East Baltimore in a Polish working class neighborhood of row houses, storefronts and taverns, not far from the Baltimore port. Her grandmother and mother were strong-willed women who knew everybody in the neighborhood. In addition to Mikulski's Bakery, her family ran a small grocery store, called Willy's Market, where neighbors would gather to exchange gossip.

Mikulski attended the Sacred Heart of Jesus Elementary School and the Institute of Notre Dame High School in Baltimore. "The nuns were a source of great inspiration," said Mikulski, who as a teen-ager considered becoming a nun.

As a young girl, during hopscotch games, she lectured playmates on civics, according to her uncle, Edward M. Blazucki. And when the nuns urged the youngsters to collect enough money for each class to "adopt" a baby in China for $5 apiece, "that wasn't enough for Barbara. She said, 'I want my own baby,' " said Fran Liszewski, her younger sister.

"So she scrounged and saved up $5, on her own, so she could have her own so-called pagan baby," her sister said.

As a child, Mikulski was energetic and outgoing, her family said. But she lacked the characteristics that often put girls in the "in" group in parochial schools -- athletic prowess. "Athletics was one way of being in the limelight," said her sister. She said Mikulski tried out repeatedly for all the teams but never made any of them.

Eventually, however, Mikulski discovered she had good comic timing. She became a favorite at the Catholic Youth Organization's variety shows, and she organized neighborhood plays. "I was always organizing shows out of the garage . . . . I was the writer, director, producer and the star," Mikulski said with a laugh.

Willy's Market burned down when Mikulski was in her teens. But despite the enormous loss, Mikulski's father insisted that she attend Mount Saint Agnes College, now a part of Loyola College. She earned an undergraduate degree in social work, and later a master's degree in social work from the University of Maryland. During those years, she also worked in a number of Baltimore social service programs.

"She was a rabble-rouser . . . a little bit militant. By that I mean, when you work for a bureaucratic agency, there's a lot of red tape. She was outspoken. She wouldn't accept it," said Irene Reid, who worked in the public welfare department in the 1960s with Mikulski, and who is the mother of Kurt L. Schmoke, the state's attorney for Baltimore.

The red tape "drove me crazy," said Mikulski, and she started looking for ways to change the system. Her first step was to persuade a fellow social worker, Gerry Aronin, to go with her to visit William Donald Schaefer, then a savvy member of the City Council and now the mayor of Baltimore.

"We told him that we wanted a lesson in how City Hall operates. He was just taken aback that two social workers were asking this," said Aronin, but Schaefer obliged. "We sat with him for quite a while."

That lesson proved to be invaluable when Mikulski and Aronin needed City Council approval for a poverty project a couple of years later. The two social workers followed Schaefer's advice: They organized the churches in the districts of the undecided members, and they won, by one vote.

Her tiny City Council victory gave the exultant Mikulski her first taste for political fighting and, coinciding with a new spirit of activism stemming from the assassinations of Martin Luther King Jr. and Robert F. Kennedy, instilled in her a sense that the political system needed changing.

"Barbara was heavily influenced by the Catholic experience" and by her years in parochial school, being taught that "you're supposed to do good works. Your role models aren't corporate presidents, they're saints who dedicate their lives to others. A sort of ethnic noblesse oblige," said Toni Keane, a sociologist who lived in an apartment across the hall from Mikulski.

Mikulski became particularly interested in helping her old East Baltimore neighborhood, feeling that the political system most often ignored poor working families and the elderly. She got involved in a fight to block a proposed expressway that would have gone through Fells Point and other ethnic East Baltimore neighborhoods.

Undaunted by the prospect of fighting City Hall with few supporters, Mikulski displayed a flair for publicity and creativity that helped her dupe the press and political establishment.

"Originally there were maybe 12 of us, and we used to meet several times a week under different group names. We would call community meetings and the press would come" and report that there was a groundswell of support because there were so many different groups opposed to the expressway, Mikulski said, chuckling.

Mikulski then began to think about running for the City Council, and she announced her plans to family members during Easter dinner in 1971. Her family, like others in the neighborhood that brought up daughters to get married, was shocked.

"At that time I was going around with one of our longtime friends, Al Figinski . . . . I sat at the kitchen table and said, 'Mom, Dad, I'm going to run for the City Council, and Figinski is going to help me.' And my mom replied, 'Barbara, you ought to run after Figinski, and I'll help you.' "

But her family supported her successful campaign and she stayed on the council for five years, a tenure that was sometimes tumultuous.

"When she was a City Council person, she may have appeared so strong an advocate that she couldn't compromise. That's the impression left by her style," said Schmoke, who said he is neutral in the Senate race. He added that he believes that Mikulski's style changed during her years in the House, when she learned how to trade votes and get things accomplished.

Mikulski ran for the House in 1976. Although she had lost a 1974 underdog challenge to Mathias, the Senate race and her appointment in 1973 as chairwoman of the Democratic Party's delegation selection committee had raised her profile.

But one doubt lingered: Would voters think that she conveyed the image of a member of Congress? To increase her appeal, she lost 45 pounds, changed to more stylish eyeglass frames and started wearing scarves and jewelry.

Even with the changes, she never achieved chic or sophistication and, according to a woman at a recent function in Dundalk, has always remained "one of us" to the people at home.

"She relates to working class people," said former state senator Harry McGuirk, a Democrat from south Baltimore. "She concentrates on bread-and-butter issues that talk to the everyday citizens: Do I have a job? Will I get enough unemployment to take care of my family?"

Mikulski said she has spent her 10 years in the House on issues such as the Port of Baltimore, Conrail, child care, health care for the elderly, assistance for displaced homemakers, hospital cost containment and a new football team for Baltimore.

Mikulski is a member of the House Energy and Commerce Committee, which she likes to describe in this exaggerated but humorous way: "If it's not a farm, if it's not a missile, and if it's not a tax, it's in the Energy and Commerce Committee." She is also a member of the House Merchant Marine and Fisheries Committee, which deals with legislation involving coastal zone management and the fishing industry.

By 1984, after surviving some low points with her staff a few years earlier, Mikulski had become a key player in the House on such issues as the environment, health, consumer issues and railroads. She also had emerged as a nationally known champion of women's rights, and was one of a few female politicians mentioned as a possible running mate for Democratic presidential candidate Walter F. Mondale.

Mondale eventually chose then-representative Geraldine A. Ferraro, and Mikulski reportedly was crushed. But she energetically rallied support for Ferraro, and the following year she began laying plans for the Senate race in which she is now running, as she puts it, as a "common-sense Democrat . . . a fighter with heart."

As for the question of her senatorial image, which continues to crop up, Mikulski has a final answer. "I hope I don't look like a traditional senator," she said. "My image is me."