Two former foes from a bitterly divided D.C. school board and a congressional aide are competing in the Sept. 14 Democratic primary for an at-large seat on the D.C. City Council--a contest that has been obscured, but also influenced, by the Democratic races for mayor and council chairman.

Incumbent council member Betty Ann Kane, 41, is fighting to keep her seat in the face of challengers from at-large school board member Barbara Lett Simmons, 54, and House District Committee staff counsel Johnny Barnes, 33. It is a trio of candidates with striking differences in style and personality.

Kane and Simmons have both won citywide elections in the past and were initially considered the frontrunners. But Barnes has raised more campaign money than either of the others, according to figures provided by the candidates.

(Last week, the D.C. Board of Elections and Ethics disqualified two other Democratic at-large candidates, Patricia Wells and Osie Thorpe, because they failed to collect the required 2,000 petition signatures needed for nomination.)

Kane and Barnes both say they believe the major campaign issue is the city's recurring budget crisis, while Simmons says the major issue is Kane's record.

Simmons charges that Kane, who spent most of the year running for mayor and only recently decided to seek her old seat, still really wants to be mayor and is running for reelection to stop Simmons. "The incumbent doesn't really want to be on the City Council," said Simmons in a recent interview. "The incumbent wants to run the city."

Many of Kane's strongest backers are public school activists who contend that Simmons' often confrontational style on the school board has hurt the board's reputation and would be a negative force if transferred to the council.

In a recent interview, Kane, who cited fund-raising problems as her reason for dropping out of the mayor's race, disputed the suggestion that the theme of her campaign is to stop Simmons. "I never run for something because I want to stop someone else," she said. "I never run a negative campaign."

She said she received "overwhelming calls . . . there was a real public response to keep me on the council . I decided to run for council because that's what people wanted me to do."

Simmons and Kane served on the school board together in the mid-1970s and became members of warring factions in the board's turbulent 1975 battle to fire school superintendent Barbara Sizemore. Simmons was Sizemore's leading supporter, while Kane joined the board majority that voted to fire the superintendent.

This is the first election in which the two have faced each other.

Kane, who lives on Capitol Hill, won a six-way race in 1974 to finish the unexpired school board term of Marion Barry, who won an at-large City Council seat that same year. The following year, Kane won a full four-year term on the school board, and then in 1978 successfully ran for her at-large council seat, winning in a field of nine.

On the council, she has gained a reputation for being pro-schools and a friend of real estate interests. She was the lone council member who voted in 1979 against imposing a sweeping moratorium on the conversion of apartments to condominiums.

She also has a reputation for doing her homework, although she has been criticized for being satisfied to vote to further her own interests rather than attempting to change the council's mind on important issues.

For example, Kane was the only council member to vote against a bill that would have raised the cost of inheriting property in the city by about 40 percent. An embarrassed council later retracted the measure following widespread public protest, and some members grumbled that Kane had not sought to make a difference on the initial vote and instead had merely acted to protect herself.

"It's important to have someone there who reads the stuff," said Kane in a recent interview. And despite the private complaints of some council members, she has been endorsed by four of her colleagues, including H.R. Crawford (D-Ward 7), whom she defeated in the Democratic at-large primary four years ago, John A. Wilson (D-Ward 2), Polly Shackleton (D-Ward 3), and mayoral candidate John Ray (D-At Large).

She cites as her most important legislative accomplishments council passage of her legislation requiring the mayor to disclose more information about city funds, her contributions to the compromise no-fault auto insurance measure that the council passed earlier this year, and her legislation to simplify income tax returns for D.C. residents by conforming city tax laws to federal ones.

Barbara Lett Simmons convincingly won her third term on the school board last year and then decided to run for council this year "because I have done my job on the school board. What is blatantly clear is that the City Council needs someone who is creative and innovative."

Her major campaign issue is Kane's record. "I feel I have upwards of 20 years experience for the people of this city," Simmons said. "The total quality of life in this city has been my interest. She Kane does not have a record of having served this community in all respects. She does have a record of serving herself."

Simmons listed as her major accomplishments helping to establish Neighborhood Planning Councils in the early 1970s that assisted summer recreational activities for youth, allowing teachers and parents to help school administrators and board members design new schools and serving as a founding member of the Ward 4 Democratic Club.

While some view Simmons as one of the most vocal members of a fractious board minority, she views herself as "a constructive advocate and innovator who is willing to fight for people's rights. I don't believe in anyone being taken advantage of."

Simmons, who lives in Ward 4, has also been active in Democratic politics, attending the 1976 and 1980 national Democratic conventions as a delegate for former president Jimmy Carter.

Simmons led the field of at-large candidates in the 1973 and 1977 school board races. Last year, she came in second to the Rev. David Eaton, who was subsequently elected board president.

Johnny Barnes, who two years ago ran unsuccessfully for the Democratic nomination to the City Council from Ward 7, where he lives, says he entered the at-large race after Kane decided to run for mayor because "with the incumbent not running that opened up the race."

With Kane's return, he says, "I think I'll have to work much harder to win."

Barnes, while admitting that he is not as well known as Kane and Simmons, says name recognition can be a two-edged sword.

"There are negative factors associated with both Kane and Simmons , and I intend to capitalize on that," said Barnes in an interview. He declined to explain the "negative factors," saying, "I don't get into that kind of campaigning."

Barnes, a lawyer, says his record includes giving legal assistance to city tenant groups. Barnes has spent seven years on Capitol Hill, first as legislative counsel to D.C. Del. Walter E. Fauntroy, and he takes credit for writing the proposed constitutional amendment to give the District full voting rights in the Congress.

According to figures supplied by the candidates, Barnes has collected the most in campaign contributions, nearly $30,000, while Kane has received approximately $20,000 and Simmons less than $10,000.

The at-large race has been overshadowed and shaped by the mayoral and council chairman campaigns.

Former City Council chairman Sterling Tucker, after deciding not to run for mayor, briefly considered running for the at-large seat, only to end up now locked in a three-way race for his old job as chairman. Kane, the incumbent, first ran for mayor, then in June decided to run for her old job.

All three candidates complained that their race has been all but forgotten. "They are yawning at the at-large race," says Barnes, echoed by his fellow candidates.