Growing disparity between white and black perceptions of Jimmy Carter's performance as viewed from his own backyard poses political problems for the beleaguered president, embodied in this question:

Can President Carter hold the 90 percent-plus black support he gained in 1976 without endangering his support by whites with their wholly different values and standards of what makes a good president?

On issue after issue, Carter gets a dramatically different reaction in two neighborhoods - one black, one white - in Georgia's 5th congressional district on Atlanta's southwest side.

By a 15-to-1 ratio, 50 black voters we interviewed in trim houses along quiet, tree-lined streets approved of the way Carter is handling the national-security issue. But in the nearby middle-income white neighborhood, 40 white voters came down stridently against the president by a 4-to-1 ratio.

This disparity runs deep, with 30 blacks giving the president a "good" or "excellent" rating but not one white scoring him "excellent" and only 9 "good." To black voters here, the president is one top of his job. The recurring complaint of whites was broken promises and lack of presidential qualifications.

A white 30-year-old salesman explained why he wishes he had voted for Gerald Ford instead of Carter: "He doesn't know what he's doing half the time." Another white defector, a 41-year-old lift operator, blamed Congress for lack of cooperation, but told us Carter "has shown his inexperience," adding, "The most important problem in the country today is getting men capable of running our government."

Armed with questionnaires prepared by Patrick Caddell's Cambridge Survey Research, we interviewed voters in two precincts with the help of Judy Tannenbaum, Caddell's top Atlanta field representative, and four poll-takers. Black precinct 9E gave Carter 97 percent support in 1976. White precinct 8P gave him 61 percent support.

Our political scouting expedition showed continuing immense strength for the president in the black precinct. "He's been traveling the world for peace," a middle-aged black housewife told us. A young truck driver praised his "honesty." A 25-year-old woman said that "putting Andy Young in the United Nations" had helped make Carter a good president.

Aganist this black approval were implications that Carter's white southern base is eroding. His greatest voting gains in the country over recent Democratic presidential tickets came among white southerners, who gave him about 50 percent support - far above recent Democratic nominees.

Of the 40 white voters we interviewed, 25 said they backed Carter in 1976, 10 picked Gerald Ford and 5 would not say. Today the president keeps only 17 of those 25, with 5 defectors moving to Ford and 3 to "don't know."

A 39-year-old sales engineer epitomized the white criticism: "Carter hasn't kept his word. He is a weak president who hasn't demonstrated the strength he promised in the campaign."

No such defections showed up among black voters, who gave Ford not a single vote in 1976 and wouldn't today. Their only change was hesitation: 4 of the 40 pro-Carter 1976 voters have switched to "don't know" today. Indeed, Carter gets extraordinary credit from black voters here. He has "cut expenses in the White House," "helped the solar program" and "visited countries no other president ever went to."

The president's "handling of the Soviets" was approved by half of the blacks but with two out of three whites calling Carter "too weak." Only three blacks, but more than half the whites, criticized Carter for spending "too little" on defense. Only on his efforts to solve the Arab-Israeli struggle did the president get high marks from almost everyone: 82 of 90 approved, a remarkably high score.

The president's standing with black voters could be hurt if he shifts into a harder anti-Soviet posture, forcing an increase in defense spending (at the cost of federal job subsidies and welfare programs) - clearly desired by a majority of the white voters interviewed. Or he could risk black reaction if he switched to a tougher anti-Cuba policy in black Africa, particularly if U.N. Ambassador Young - a hero to blacks here - raised objections.

But Carter's problem today clearly is not blacks, but whites. Given the wide contradictions between white and black views of his presidency, he may have to risk colliding with the views of his overwhelming black constituency to shore up his fading white southern support before 1980.