'TIMES have changed, and he's not the same old Maynard," notes an observer of Atlanta's political scene. Maynard Holcomb Jackson, Atlanta's first black mayor when elected in 1973, has matured. He no longer has to establish his credibility, but there are new challenges to face and a new strategy for meeting them.At 35, the Maynard of the 1970s was one of the youngest and most aggressive mayors in the United States. He served when Atlanta was making the difficult political and social transition from white power to black power. His greatest "brick and mortar" achievement, he boasts in a booming baritone that has become his trademark, was the building of Hartsfield Airport under Affirmative Action guidelines and joint-venture agreements with black contractors. Mayor Jackson envisioned Atlanta as a national model for affirmative action programs. He upset the white establishment, pushing to open up City Hall, as well as some of the city's oldest businesses and institutions, to all citizens. But some community leaders felt that he was often brash and confrontational, particularly when enforcing the city's minority hiring policies. After Jackson had served for eight years (the city charter allows a mayor to serve only two consecutive terms), Atlanta remained a center for black power. Andrew Young, a former US congressman and ambassador to the United Nations, served as mayor from 1982 through 1989. During the eight years he was out of office, Jackson worked as a successful bond lawyer, earning a six-digit salary. He became more attuned to the role the business community plays in the overall economic well-being of a city. When he decided to run for mayor again, Jackson won the support of the business community as well as the most affluent white neighborhoods. He won with 80 percent of the vote, carrying all of the city's 187 precincts. In his inaugural address, Jackson promised to work "hand-in-glove" with the city's business community. He has developed a better relationship with that community, including some of the city's most powerful bankers and developers. But some civic leaders express doubts about the Maynard of the '90s. Some question his accessibility and willingness to listen to those outside his inner circle. Dan Sweat, former president of Central Atlanta Progress and the coordinator for Jackson's transition team, says, "Maynard still needs to hold out the olive branch to avoid the type of fights he had during his first term and maintain [the white business community's] support." While Jackson was working in the private sector, the city he led from 1974 to '81 also changed. Known for its boosterism and hospitality, Atlanta struggled to gain a reputation as a convention center and international hub. And the efforts paid off: Atlanta has been selected to host the 1994 football Super Bowl and the 1996 Summer Olympics. But despite recent achievements and successes, the "city too busy to hate" has one of the nation's highest crime rates, among other problems. Twenty-seven percent of the city's population lives below the federal poverty level, and economic forecaster Donald Ratajczak predicts that Atlanta will lose 13,500 jobs this year. There are 10,000 homeless people in the city, an increasing number of them in families. There is a growing gap between haves and have-nots, and the city's infrastructure - roads, bridges , and sewerage system - is crumbling. Like other big-city mayors, Jackson is facing a budget crisis, a cutback in city services and possible layoff of city workers. While he is relentlessly upbeat, he admits, "It's tougher this time around - there are fewer state and federal dollars and there are four issues on my plate that weren't even mentioned in the 1981 budget AIDS, homelessness, drugs, and potable water. Jackson promised to hire 500 new policemen but has not had the funds to do so. However, he has won praise for his attention to public safety. Gene Dyson, president of the Business Council of Georgia, says, "He's spending a lot of quality time managing the city and making it work." The city's crime problem remains Jackson's No. 1 priority. He appointed Eldrin Bell, considered a tough, "old-fashioned cop," the chief of police. For the first time in seven years, the city's overall crime rate decreased last year, by 14 percent. As a member of the Metropolitan Atlanta Olympic Games Authority, Jackson sees the games as a tremendous economic opportunity. He vows that the city will not be left with a major debt as Montreal was in 1976. A self-proclaimed champion of the underdog, he says, "We will not sweep the poor and homeless under the rug." He recently announced an ambitious plan to revamp 15,000 homes that includes single-room occupancy units and traditional housing units. The plan depends on funding from the US Department of Housing and Urban Development in addition to funding from public and private sources. With his characteristic confidence, Jackson says, "I am convinced that getting the private sector involved in rebuilding th e infrastructure and providing housing will save American cities. The private sector creates jobs and makes a profit, and the city gets a service. It's a win-win proposition for everyone." Joe Beasley, spokesman for Georgia's Rainbow Coalition and the political chairman of Atlanta's Concerned Black Clergy, says of Jackson: "His heart's in the right place, and he's making good-faith efforts to put together the creative financing needed to provide low-cost housing." Some community activists feel that Jackson has hindered rather than helped progress on building single-room occupancy units promised over a year ago. Anita Beaty, co-director of the Task Force for the Homeless, says, "It's a shell game. There's a lot of talk from City Hall, but no substantial action or funding." Critics say the mayor, once known as "Action Jackson," has been slow to pull his management team together and "get things moving." There are allegations of inefficient financial management and cronyism. The local press reports that Jackson's personal friends continue to land lucrative contracts for city work. Despite problems at home, Jackson maintains a strong national reputation. Some observers expect him to get into national politics in 1996.