In the bitter cold they are marching on the South African embassy. For more than two months a crowd diverse in race, background and income has revived the strategy of demonstrations and civil disobedience. Just before the daily arrests begin, Randall Robinson, an imposing figure in a tweed cap and navy blue greatcoat, steps forward to speak:

"We will be here in the cold . . ."

The crowd edges closer. Cars barrel by on Massachusetts Avenue, honking their horns in a show of support.

". . . We will be here in the snow. We will be here in the sleet and in the rain. Day in, day out, week in, week out, month after month. We will not leave until our demands are met."

Robinson, 43, is the national coordinator of the Free South Africa Movement, which has organized the actions at the embassy. Since the civil rights initiatives of the mid-'60s, the sight of an integrated protest movement of any scale has been rare. The Free South Africa Movement is a revival of both the spirit and tactics of 20 years ago and Robinson, who is also the executive director of the TransAfrica lobbying group, is the principal organizer.

"This is an open movement, not a club movement," he says. "This is a basic issue focused on a system so vicious that anyone who believes in what our country is supposed to be about is likely to find a place in this coalition."

Among the 45 people arrested on this January day is former tennis champion Arthur Ashe. Both Ashe and Robinson grew up in segregated Richmond and joined the civil rights movement.

"It's been a hell of a long time since you've seen blacks and whites from all different backgrounds marching together about anything," says Ashe. "Randall should be proud of that. We all should."

Randall Robinson has seen South African racism firsthand. He and a congressional delegation stopped in South Africa for several days en route to a conference in Sierra Leone eight years ago.

But Robinson did not need to visit Cape Town or a black "homeland" to understand the misery of racism. As a boy he used to walk down Richmond's Monument Avenue past huge statues of the Confederate dead looming above him -- Robert E. Lee, Stonewall Jackson, Jefferson Davis. Richmond was a city of segregated theaters, stores, schools and neighborhoods, a city divided by segregation and the question of what to do about it. Robinson remembers "columnists like James Kilpatrick calling for massive resistance against integration and practically standing in the schoolhouse door.

"They never let you forget that Richmond was the capital of the Confederacy. I remember going with my mother to a department store and she'd have to put on a little cap before they'd let her try on ladies' hats. I recall sitting in the back of the bus with lots of empty seats up front. I remember delivering groceries to a white home, and when I came into the kitchen and they were discussing something very personal, they never stopped talking. It was as if I wasn't there. I was invisible."

But the South African experience was even more painful. As he stepped off the plane, Robinson says, he "could feel it right away, a whole society that smells of tension. Everyone is watching everyone. It's a situation that feels like it might explode at any moment. It's almost surreal."

Robinson got his first taste of apartheid at the airport. A sign above the men's room warned him against using the facility. One of the white members of the delegation had to accompany him into the bathroom.

"I remember being so, so angry," Robinson says. "The scab had been pulled off an old wound. But this was not only a segregated state, it was a police state."

The delegation met with a group of white South African businessmen. The question of giving blacks the right to vote came up and the businessmen were stunned.

Robinson remembers, "They told us that giving blacks the right to vote was like putting a gun in the hands of a 5-year-old."

Minutes later in an adjacent room, the delegation met with Alan Boesak, a black African minister who has become an important leader in recent years.

"The contrast between the businessmen, and their casual description of apartheid, and Alan's description of the horrors of the system was unforgettable," Robinson recalls. "It was like two ships passing in the night. All of a sudden I realized how irreconcilable the positions are. And I saw how either blacks strike out in some way against the oppression or they turn their anger inward and begin to hate themselves and become stooped human beings."

Robinson lives in Northwest near Walter Reed hospital. He was recently divorced after 18 years of marriage. His two children, 13-year-old daughter Anike and 9-year-old son Jabari, divide their time between their father and mother.

During an interview in his small office at TransAfrica, Robinson sets a different tone than he does behind the podium near the embassy. He is measured, professorial, careful, constantly aware of forming coherent paragraphs of thought. At certain points, however, he is relaxed and emotion surfaces -- anger at South African apartheid, tremendous pride in his family.

The Robinsons were famous in Richmond. Maxie Robinson Sr. taught history and coached nearly every sport offered at Armstrong High School. Doris Robinson was active at the Fifth Street Baptist Church.

Their four children made their own mark: Jewell Robinson Shepperd was the first black student at Goucher College. She has been a fundraiser for the Urban League and is now working as an actress. Max Robinson was the nation's first black television anchor. He is now a local television anchor in Chicago. Jean Yancey is the public relations director at the Duke Ellington School of the Arts. (Maxie Robinson Sr. died in 1973. Doris remarried and still lives in Richmond.)

"My father was very involved in keeping us all close," says Jean Yancey. "When I think of our family and how close it was, and how close it still is, I think of Nikki Giovanni's line, 'Black love is Black wealth.' I never saw us as being poor."

"Everyone in town knew us because of our parents. It wasn't easy to make a wrong move," says Jewell Robinson Sheppard. "My parents also tried to protect us from the worst aspects of segregation. They were especially protective of the girls. There were places you just didn't go, things you just didn't do. But there was no hiding the facts. You never get over that feeling of apartheid in Richmond."

Arthur Ashe remembers a whole generation of talented black students and athletes who grew up in Richmond in the 1950s, but, he says, "we all left. You had to leave."

Randall Robinson says he never had a conversation with a white person until he was 22 years old. "I can't even remember what we talked about," he says.

He never sat next to a white in a classroom until he began Harvard Law School when he was 26. "But I was lucky," he says. "I never grew up thinking or suspecting I was inferior. My family would never have let me fall into that."

Robinson took an undergraduate degree in 1967 at Virginia Union University. At law school he became friendly with Harvard president Derek Bok, then dean of the law school. After graduation, Robinson stayed in Boston to work as a public interest lawyer. When he returned to Boston after a six-month sojourn in Tanzania, Robinson and others occupied Bok's office as part of a protest against Harvard's investments in companies doing business with South Africa.

Since then, Robinson says, "Derek and I haven't been in touch."

For a while Robinson was an aggressive foreign affairs aide on Capitol Hill, working first for Rep. William L. Clay (D-Mo.) and then for former Rep. Charles C. Diggs Jr. (D-Mich.), who was later convicted of taking kickbacks and left the House two years later.

Diggs, Robinson and a number of black representatives sensed a vacuum on the Hill. There were lobbies for Israel, for Arab interests, for nearly every nation, industry and cause possible. But, according to Robinson, "nobody ever heard much about Africa. One prominent member of Congress told me there weren't more than a few people on the Hill who could name more than three African countries."

The Congressional Black Caucus met in the fall of 1977 and held a special seminar to create a lobbying group for Africa and the Caribbean. TransAfrica was born.

"The whole project was run out of my office until we had enough funds to start a separate office and Randall could take it over," says Diggs. "What we're seeing now at the embassy is the fruit of a lot of years' labor. It's what TransAfrica was meant to do."

In the past nine years, TransAfrica has grown in size and influence under Robinson's direction. It has an operating budget of $300,000. Robinson, whose salary is $34,000, tries not to see himself as a leader ("Maybe a coordinator").

Consciously or not, Robinson's personal demeanor, his methodical, unobtrusive style of leadership, acts almost to offset political beliefs that are deeply opposed to those of the present administration. He dresses as conservatively as his adversaries. The old garb of militancy, the combat boots and dashikis he once wore, are long gone.

"I never liked the term 'militant,' " Robinson says. "It implies a certain mindlessness. In the movement, we never thought it was a mistake that blacks were militants and whites were radicals. I think of myself as a humanist. The whole issue of leadership can have racist overtones. Nobody ever talks about 'white leadership.' The business of 'black leadership' or 'Indian leadership,' whatever, is a device used to obviate examination of particular issues and problems."

None of Robinson's friends and peers think he has changed much.

"You see, we all wore dashikis in the old days," says writer and activist Roger Wilkins. "Randall, remember, is a Harvard-educated lawyer. He was never a street organizer the way Marion Barry was.

"If I had to compare Randall to anyone, it might be the late Roy Wilkins. He has that same polish and savoir-faire, but Randall's got a lighter touch. He's not as austere as my uncle was. And, of course, Roy was more conservative in substance. I don't think Randall enjoys the attention much. I've never heard him express a yearning for more money or higher position."

Every afternoon, Robinson's demands are the same. To the South Africans: Free all political prisoners. Create a new constitution that would enfranchise the country's 73 percent black majority. To the Reagan administration: End the policy of "quiet diplomacy" toward the South African government known as "constructive engagement." Exert political pressure and economic sanctions on the South Africans. And to American companies doing business in South Africa "where you are doing more harm than good": Simply, get out.

After the first arrests on Nov. 21, some critics suggested that black leaders saw themselves in dire need of a unifying issue, one that would draw maximum news coverage and maximum attention to the problems of black Americans. Marches and passive resistance, two of the staple tactics of the civil rights movement, have indeed put the South African issue back in the headlines, but Robinson argues that he and his fellow leaders did not make their choices cynically.

"I'm sure the catalyst for this starting when it did was Reagan's reelection," Robinson says. "The South Africans understand the Reagan administration to be in their corner and felt his reelection was a green light, four more years of license.

"But to suggest that the black leadership put down all of its domestic concerns and decided on the South African issue as a means to resurrect the movement is absurd. It just didn't happen that way.

"In no country in the world is racism as culturally enshrined as it is in South Africa. By the very color of your skin, you become an automatic victim -- rightless, voteless, and ultimately lifeless. That exists in no other country in the world and that is why the world community, and the mix of people who come out every afternoon, have isolated the country of South Africa."

TransAfrica itself has been the center of some controversy in recent years. The group holds an annual fund-raising dinner featuring a keynote speaker. The speakers have included black American leaders such as Atlanta Mayor Andrew Young and Georgia state Senator Julian Bond and foreign leaders with a decidedly leftist viewpoint: Michael Manley, the former leader of Jamaica; Maurice Bishop, who was prime minister of Grenada until he was assassinated in 1983; and Sam Nujoma, the leader of the South-West Africa People's Organization (SWAPO).

John Chettle, president of the South Africa Foundation, says, "Obviously, TransAfrica takes a radical line on South Africa and American foreign policy in general. Look at their speakers. Isn't it a curious thing for an American organization to be consorting with people who are so anti-American?"

Robinson contends that an invitation to speak at the TransAfrica dinner is not a blanket endorsement of the speaker and that such engagements are intended to let "alternative voices be heard."

Robinson and his fellow protestors are demonstrating not only against apartheid but also against the Reagan administration's course of "constructive engagement." Assistant Secretary of State for African Affairs Chester A. Crocker, who is the prime architect of the administration's policy, contends that South Africa is slowly easing the strictures of apartheid, recognizing black trade unions and increasing spending on black education and welfare.

"There has been more reform now in South Africa than there has been since World War II," says Crocker.

Robinson contends that while the South African government may make certain "cosmetic" changes, the Reagan administration has made it easy for South Africa to keep the nation's 4.7 million whites in power.

Recently 35 conservative congressman, led by Rep. Vin Weber (R-Minn.), wrote a letter calling on the president to get tougher with South Africa. South African Anglican Bishop Desmond Tutu, who won the Nobel Peace Prize last year, has called "constructive engagement" "immoral, evil and totally un-Christian."

"We've seen virtually a carte blanche endorsement of anything the South African government wants to do," says Robinson. "I think the Reagan administration has essentially sought to cement a relationship with what it sees to be, or what seems to be, a relatively stable, anti-Soviet regime. These global interests, perceived rightly or wrongly, cannot be reconciled with that country's policies toward three-quarters of its population. The regime is inherently unstable and will be toppled. Any new regime is not likely to look kindly on our support of tyranny."

Robinson's goal for South Africa "is to negotiate a constitution that will be fair and equitable so that all South Africa can build a society free of vicious racism."

But even his most optimistic scenario for a transfer of power in South Africa includes violence:

"Anyone who sees the gulf between the black and the white, the victims and the victimizers, has to know immediately that the white majority is not, voluntarily, going to give up power. What we're trying to do, and what Bishop Tutu is trying to do, is appeal to the United States to impose the pressure necessary for the South African government to seize a last opportunity to minimize the prospect for disaster and bloodshed."

Critics, including an official at the South African embassy, argue that if the South African government is pushed too hard, its resolve will harden and leaders to the right of President P.W. Botha will gain more influence.

Robinson laughs at the suggestion that the situation in South Africa could get any worse for the black majority.

"Harden their resolve?" he says. "We used to hear that same thing in this country 20 years ago! It won't be easy, but we survived slavery. We survived Jim Crow. We will survive apartheid."