If there's a bakery vote in politics, Barbara Mikulski has it. The Baltimore Democrat -- a five-term House member now running for the Senate -- remembers her first political race in 1971. To help support a large Polish family, "my grandmother on my dad's side opened the Mikulski bakery shop. When I was running for the city council and challenging the machines, I'd knock on the door, and they'd ask, 'Are you any relation to Mikulski's bakery shop?' and I'd say, 'Yeah.' And they'd say, 'Listen, if you're half as good as your doughnuts and half as nice as your grandmother, you'll be okay.'

Capturing the bakery vote and adding it to her coalition of ethnic, working-class and community-activist supporters, Mikulski went on to win a seat on the Baltimore City Council. Her politics became an extension of her earlier commitments as a welfare department social worker among the families of southeast Baltimore. In 1976 she came to Washington to represent the third district of Maryland.

In her office the other afternoon, while dieting on a lunch of cottage cheese and a sliced banana, Mikulski was emphatically the daughter of all she has touched and seen. The Highlander neighborhood, where her Polish immigrant grandparents settled, is where she lives today. The lunch-pail factory workers and shopkeepers she served for five years on the city council are the ones she listens to now in her drive to be "a common-sense Democrat."

What she is most sensible about is the refusal to let herself become packaged and blow-dried. At 4 feet 11 and with the heft of a stevedore and a voice to match, she is unique on the Democratic left: among its limousine liberals, Mikulski is a stick-shift populist.

Mikulski's political career of urban populism began with a successful protest. In 1968 she rallied citizen opposition against a proposed 16-lane highway through her neighborhood. Mikulski's political philosophy was being shaped in those years by three people: Saul Alinsky, Dorothy Day and Geno Baroni.

Alinsky was the Chicago writer ("Reveille for Radicals") and community organizer who believed that "power never yields voluntarily." Day, who co-founded the Catholic Worker movement, which has fed and sheltered millions of the homeless since 1930, taught Mikulski that reform begins not by setting elaborate goals but by creating the conditions "where it is easier for people to love." Baroni, a monsignor who was to become an assistant secretary of HUD in 1977, counseled Mikulski in the ways of building coalitions among minorities to make a force as powerful as the ones oppressing them.

With the thinking of those three as her ideological base and the neighborhoods as her political base, Mikulski is a Democrat who succeeds locally while her party flops nationally. She won reelection in 1984 with 68 percent of the vote, while Ronald Reagan took her district.

"What's wrong with the party?" she is asked. Like other progressive Democrats, Mikulski is bedeviled by the party's failure to convince the public at the national level that its social and economic programs have benefited the country: "I think what people confuse our party with is the difference between being progressive and permissive. Democrats believe in a progressive society: the expansion of democracy, the expansion of opportunity, the expansion of self-help. At the same time, that has often been confused with the permissiveness that has generally occurred in our society and has had nothing to do with the Democratic Party."

The latest polls put Mikulski far ahead of several conventional-stripe rivals. The lead is doing nothing to slow her campign. Nor is it turning Mikulski into another cautious front- runner. She insists on having a light side. She tells a wry story about growing up Catholic.

While a student at Mt. St. Agnes College in Baltimore, Mikulski thought about joining a religious order. She laughs at the idea of someone like her taking vows: "The vow of obedience did not have a great appeal to me. Poverty was one thing and I could go along with chastity. But it was obedience. I thought, 'My God, all my life there could be someone telling me what to do and where to go!' And inside me beats the heart of a protester!"

It is known that when Mikulski has personal money to get rid of, it goes to such worthies as the Sisters of Mercy, the Carmelites and the nuns in whose parochial schools she learned the principles of moral living.

Mikulski is not yet a national Democrat, although many of her legislative successes for women's equality, worker safety and consumer rights have benefited as many outside the district as her work to improve the Baltimore harbor and clean up the Chesapeake Bay have helped those inside. She has a philosophy of power that is national, or at least should be: "The people who are the most affected should have the most to say." That stopped the highway in 1968.

It also explains Mikulski's boundless faith in her constituents' taste for quality doughnuts and Polish congresswomen.