Deborah Ragland Marshall, the only black woman ever elected to the Prince George's County Council, says she has always felt like an outsider in the county. "I felt like a token from day one, when I worked in Winnie's (former county executive Winfield M. Kelly Jr.) office," said Marshall, who, at 27, was also the youngest person ever elected to the council.

"For the ticket I was a two-fer, and a three-fer--young and black and female," she said, with a candor that had increasingly irritated the Democratic organization that launched her to the at-large council seat in 1978. "I think I've gone beyond that now, but then, I had to fight for a year to keep from being called a little girl."

Now this outsider who became an insider wants out again. She announced last week that she will not run for reelection to the council after having served only one term. She says it's a decision that forced her to confront the considerable difference between what she wanted for herself and what she, as the lead player in what she called a "political Cinderella story," was supposed to want.

Marshall, now 31, says she decided that she prefers government to politics, and thus will try to seek staff-level work in another politician's campaign or a job in the private sector. She says she decided she wanted to marry again (she was married briefly at a young age), and her fiance, a Philadelphia councilman, is more attached to his political career than she is to hers.

She decided, too, that she didn't really like the crowds, the pressure of public office and the intense personal scrutiny that is the bane of every unmarried politician's existence.

Marshall said that the county's redistricting, under which members represent districts rather than running at-large, had no bearing on her decision not to run, despite the fact that she would face another incumbent council member in a race this fall.

For a person who has prided herself on breaking stereotypes and charting new ground for women and minorities, this was, she said, "an agonizing decision." She said her guilt was deepened by a wave of disappointment expressed by her friends and supporters.

"What can I say? As far as I'm concerned we have a district over there that should have some representation," said Democratic state Sen. Tommie Broadwater, the county's leading black politician. "It just means I have to work a little harder. You know, I've been at this thing for a good little while and I was hoping for a breather. She was getting in a position to be a leader and she's leaving. . . . It's disturbing."

"I agonized over this for months," Marshall said, "This is an opportunity that not many black folks have. And I'm finding out that it's an opportunity not many people want to be bothered with."

She started as a $10,000-a-year community affairs assistant in Kelly's office in 1974, where a sprinkling of young black aides worked alongside what seemed like an army of aggressive, white males who, Marshall said, seemed to know all the political players and all the deals and who often called the shots.

She then became the executive director of the Prince George's County Commission for Women, and was placed on the Democratic slate in 1978. At the time, a county newspaper included her as one of four members of the 11-member council slate it said were undeserving of public support.

"There appears to be nothing in her background or qualifications that would account for the quick rise of this relatively new county resident," said the Prince George's Sentinel, which pointed out that Marshall had moved from Greenbelt to Suitland to run against an incumbent council member who had fallen out of favor with the Democratic organization. "It is clear which way she would go if, as a council member, she were faced with a conflict between the party's interest and the public's," the newspaper said. Instead, Marshall ran at-large, a decision she said was prompted by her desire to serve black communities throughout the county. Though she finished in the top three in the Democratic primary, she was fifth out of six successful candidates in the general election.

She admits that her first year on the council was spent learning the mechanics of local government, and the next two, trying to build a base of grass-roots support that most politicians bring to the job.

In the past year, the last year of her current council term, Marshall has exerted more leadership, in a direction that has increasingly veered from the paths charted by her former sponsors. She voted against awarding a cable television franchise to a firm represented by Kelly, and against the zoning for a widely supported Science and Technology Center in Bowie when she became convinced that the project was ecologically unsound. She lobbied hard for a Metro route to serve Suitland, in opposition to the group with which she's usually allied.

Despite having labeled herself one of the council's "bleeding hearts" when she assumed the vice chairmanship last fall, she also fought to shave thousands of dollars from the park and planning commission's budget this year, saying much of the money was to be used for unnecessary studies.

The only announced candidate for Marshall's seat is Robert A. Spencer, of Seat Pleasant, a two-time losing candidate for public office. Though he has earned the endorsements of two municipalities in the councilmanic district, he is not well-liked by other black leaders, who say he will be isolated on the council.

Marshall hopes that other candidates will emerge in the next few weeks and that her presence on the council will be, she said, "a legacy of encouragement to the others who may seek this office; that my participation will . . . dramatize what can be achieved by stubborn, creative, devoted determination."