Traveling by Winnebago down the steamy, two-lane highways of the Mississippi delta, William Bradford Reynolds and Jesse Jackson made an unusual couple: Reynolds, the 41-year-old, Yale-educated assistant attorney general for civil rights, former corporate lawyer and member of the wealthy du Pont family; and Jackson, the outspoken head of Operation Push, who is considering running for the Democratic nomination for president.

For two days, the public was treated to a new picture of Reynolds as he clasped hands with Jackson and sang "We Shall Overcome" or sat knee-to-knee with him in the Winnebago, sharing a fried fish sandwich.

When he returned, Reynolds immediately ordered federal registrars into Mississippi to register blacks. The action was so swift, so unequivocal and so uncharacteristic that it was as if the much-maligned civil rights chief had undergone a transformation like Saul's on the road to Damascus.

Since then, civil rights groups have lined up outside his office.

A group of 14 black ministers and lawyers from Harlem and Brooklyn jammed into the office that once belonged to J. Edgar Hoover to complain of police brutality. Reynolds promised to look into the situation.

The next day, Reynolds met for over an hour with Chinese-Americans upset about the probationary sentence given to the killers of a young Chinese man fatally beaten with a baseball bat in Detroit. Again, he promised to look into the matter.

The same day a group of blacks brought a letter of commendation to Reynolds for his prosecution of a white man in the murder, again with a baseball bat, of black jazz musician Stephen Harvey in Kansas City, Mo.

Meanwhile, the civil rights community is trying to figure out whether all this means a change in policy or if it is simply an effort by the administration to improve its image with blacks in time for the 1984 election.

Reynolds insists that he has not been "born again." He said in a recent interview that he has always had strong feelings about civil rights and voter registration. He also said that he has always been willing to meet with blacks and members of other minority groups. But until recently they haven't been as anxious to meet with him.

Reynolds said, "We have tried desperately to convey to the public that we do care about these issues, that we are trying to do something about them, that our job of enforcement is one that is carried on as vigorously and rigorously in this administration as it has been in prior administrations. And I think we have a record to back it up."

He admitted that the administration's civil rights record has created an "image problem."

"Whether it's fair or unfair that we have that image problem, I certainly intend to the extent I can to correct that. . . . If this trip helped to let people see the side we feel is the right side of the story, then I think that's tremendous. I don't feel at all apologetic about that. . . . It doesn't change why I went down there. It doesn't change what went on down there," he said.

Reynolds, who had never before been to the delta area, said that he didn't "know what to expect. I suspected probably much more of a stand-offish kind of situation where people would look curiously, would say very little and probably would be reluctant to come forward and interact.

"I came away with a much different impression. I did not get the feeling that people came to size me up and to gawk curiously but rather came to make it clear they had a story to tell . . . that these were serious problems for them."

Reynolds said that he was surprised by the warm welcome he received and said that his traveling companions--Jackson; Mississippi lawyer Victor McTeer; Aaron Henry, the Mississippi state president of the NAACP, and Leslie McLemore of Jackson State University--"helped a lot to break down what otherwise might have been some suspicions and reservations."

He said that he and Jackson have developed a friendship even though "we disagree . . . more than we agree. But, I was more surprised on the amount of things we find ourselves in agreement on.

"I like Jesse Jackson. I think he is an individual with a far greater degree of commitment about what he's doing than the public perceives. Whatever Jesse Jackson's personal ambitions are and whatever his motivations are on that side of the scale . . . I come away convinced that he has committed himself in a way that few individuals would be willing to do to this registration effort because he believes very strongly that it's right and that it's important. I admire him for that. He sacrifices an awful lot."

It is too early to tell what other action the Justice Department will take in Mississippi, Reynolds said. "There are two sides to every story. And I think I heard one side on that trip, and I want to hear what other people have to say . . . before making final judgments."

But he added that he will not let the matter drop; "we're going to follow up." He said that he plans to file new cases to make use of the Voting Rights Act, which was strengthened last year.

But Reynolds rushed to make clear that he is no closet liberal. He pointed out that he believes as strongly as ever that affirmative action quotas and mandatory busing are wrong.

"I still feel the positions we've taken . . . are absolutely correct. . . . The black community and the white community, men and women, are going to be far better served if we are searching for more effective alternatives. . . . ," he said.

"You've got a large number of the black community who step forward when somebody says 'mandatory busing' and object vehemently. You've got both houses of Congress that have independently weighed in with large majority votes against busing. . . . If we're going to continue to push with blinders on for mandatory busing. . . I think we're going to end up finding ourselves going down a dead-end street," he said.

Ralph Neas of the Leadership Conference on Civil Rights, an umbrella group of 165 organizations, has charged that the administration is playing up the busing and quota issues to attract blue-collar voters and take attention away from other civil rights issues.

"The Justice Department has been attempting to focus public attention only on the issues of quotas and busing, trying to camouflage the administration's miserable record in virtually every area of civil rights," he said, pointing to the administration's positions on free legal services, the Equal Rights Amendment, tuition tax credits and discrimination in housing, employment and education.

Reynolds said, "I don't think it's fair to suggest that it's a manipulative play that's designed to enhance the political equation one way or the other. I don't think we've tried to hide anything. We've been very up front about it. We've told everybody where we stand on these issues; we've filed papers in courts; we've made speeches.

"I'm not sure I understand the suggestion that we're playing up some things in order to camouflage others. . . .There's nothing here I've been involved with that I feel embarrassed about. . . . I'm not apologetic about anything," he said.

But Reynolds cringes when reminded of an article by Drew Days, his predecessor at the Civil Rights Division, who charged that "the Reagan administration has been attempting to wipe out civil rights gains that took two generations to achieve."

Choosing his words carefully, Reynolds said, "We think there's a need to re-examine things . . . to see if there's a more effective way to do them. You can either say that because we're daring to re-examine that which has been in place for decades, we're setting back the clock and unraveling civil rights, or you can say . . . we are endeavoring to advance the cause of civil rights . . . to get to the point everybody wants to get to.

"The end result is something everybody is striving to obtain. The means . . . is where the discussion focuses."