The No. 70 "Archives" bus from Brightwood flaps open its flexi-doors to board early-morning commuters at Georgia and New Hampshire avenues, a hub of the Petworth community in upper northwest Washington, when there is a sudden commotion.

A man pops onto the bus, wearing a green-and-white satin apron, a green-and-white T-shirt pulled over a conservative shirt and tie, and campaign bumper stickers stuck to his sleeves.

"Hi, I'm Arrington Dixon," says the man whose face is silkscreened on the T-shirt. "I'm running for reelection as chairman of the City Council. Tell your family and your friends. I need your help," he says, passing out buttons and pamphlets from the satin apron. "Please don't forget Sept. 14. Please vote for Arrington Dixon."

At the next stop he's gone, but not before slapping a bumper sticker above the rear door exit, having performed white-collar Washington's version of handshaking at the factory gate.

Off the bus, he sprints through Georgia Avenue traffic to shake hands with two commuters who honked from a red convertible. It's a good strategy, an aide remarks, as long as he doesn't get killed.

It's political survival that Dixon has his eyes fixed on now, facing two tough opponents in the Democratic primary: former chairman Sterling Tucker and Ward 1 Council member David A. Clarke.

Although many observers thought Dixon could defeat Clarke in a two-way race, most rate the three-man contest a tossup because there is no runoff and a candidate can win with less than 50 percent of the vote. There is no Republican contender.

"Sometimes it gets to be a circus out here," Dixon says on the street, but he believes enthusiastic campaigning could mean the margin of difference for him because, he says, people appreciate being asked for their vote.

Dixon's freewheeling early-morning forays are in sharp contrast to the conservative, behind-the-scenes leadership style he has pursued as head of the 13-member Council since 1979.

Handsome, articulate and a careful dresser in his role as chairman -- "an ad man's dream," one opponent said -- the 39-year-old Dixon has been criticized by Council members and others for lacking the political ability to work out legislative compromises to avoid contentious and rowdy floor fights.

Dixon, bristles at such criticisms, equating backstage political maneuvering with "backroom deals." But he acknowledges that he considers himself "an outsider" who doesn't make close personal or political friends easily, despite his friendly manner in public.

That distance has hampered his efforts on behalf on what he says is his major goal: to establish the Council as an equal branch of city government with the mayor. Mayor Marion Barry usually can command the votes of seven Council members, a majority, while Dixon cannot claim such loyalties.

Dixon attributes the mayor's influence in part to his ability to control the flow of city services. "I can't fix potholes," he says, but he adds that Council members don't realize the power they could exercise over those matters. A politically unified council, he says, "could force the mayor to fix the potholes, not go begging to him."

The issue of leadership burns deeper than politics for Dixon, the son of an Anacostia maintenance man, who was a leader in the ROTC program at McKinley High School and who worked as a waiter at private clubs to help pay his way through Howard University and George Washington University law school.

"I have always been striving," said Dixon during a recent interview, noting that he was not as active in the civil rights struggles of the 1960s as some of Washington's current political leaders because he was trying to be accepted in the established black community that flourished in Washington despite segregation.

"I went to some sit-ins and protests," he said, but his parents pushed him "to get my education, then try to change things." He considered a career in the Air Force, but decided it wasn't for him. He remains in the Air Force Reserve today. He helped design and taught a computer science class at the Washington Technical Institute, which merged with two other schools to form the University of the District of Columbia. He was first elected to the Council in 1974, representing Ward 4.

Dixon was recently divorced after 15 years of marriage to Sharon Pratt Dixon, the daughter of a prominent Washington family. Sharon Dixon, who is campaign director for Patricia Roberts Harris' bid for mayor, was considered Dixon's principal adviser and some observers believe he has suffered politically because of their breakup. Dixon, however, downplays its political significance.

This was almost an easy political year for Dixon. For a while this spring it appeared he would have no opposition in his reelection bid, but then Tucker's second run for the mayor's office collapsed and Clarke reconsidered a decision not to run for Council chairman.

Dixon complains that Tucker "is settling for the chairman race because he can't be mayor," and says his own four years as chairman are being unfairly compared to Tucker's 1975-1978 reign as the first elected Council chairman, which generally is remembered favorably.

"That's nostalgia," Dixon says, specifically recalling "endless budget sessions" and tough and open fights during those years over rent control and a proposal to abolish the school board. He points out that Tucker did not have "five Council members campaigning for higher office and one of them for my job."

"There's no walking on water. It's tough," says Dixon. "It's a matter of taking on hard issues." After several questions about Tucker's leadership, Dixon replies tartly, "I'll say one thing publicly. Sterling Tucker is a better deal-cutter than I am."

Dixon maintains that Clarke, generally considered an effective Council member, does not have the temperament to run the Council, is too quick to anger if persons disagree with him.

As chairman, Dixon was among the most visible city officials in last year's successful fight against an education tax credit initiative. The initiative was viewed by opponents as a threat to improving public education here, and fighting it was a natural cause for Dixon, who has strongly backed more money for public education.

At campaign forums, Dixon regularly mentions three bills that have passed under his chairmanship: the recently approved no-fault car insurance bill, a long-delayed measure laying the groundwork for cable television franchising and a "Council independence" bill that for the first time will give the Council complete control over its budget and its personnel system.

Dixon also has sought to improve the Council's ability to analyze the city's budgets, using computers and expanding the Council staff.

He considers the no-fault bill, which passed in the face of heavy opposition from local trial lawyers, his biggest legislative victory. One of its results, however, has been to boost support for Tucker from the trial lawyers, who are angry over Dixon's stand on the issue. Tucker has pledged to amend the no-fault law if he is elected.

Dixon has been endorsed by the city's major business groups, including the influential Greater Washington Board of Trade and the Washington Board of Realtors. He also has been endorsed by Council member H. R. Crawford (D-Ward 7) and Republican Council member Jerry A. Moore (At-large) is scheduled to endorse him Tuesday. Tucker and Clarke have yet to be endorsed by other Council members.

An Episcopalian, Dixon nurtures an interest in astrology, but doesn't talk much about it. He said an astrologist told him he would have trouble getting things together during the first half of the year.

"He must have known I was trying to raise campaign funds," Dixon joked, declining to say what the astrologist predicted for election day.