THROUGHOUT the bruising campaign for his party's nomination to a second term this fall, Democratic Gov. Ray Mabus of Mississippi told voters that his candidacy boiled down to a choice between "the past or the future."Judging by the returns in the recent party primary, many Mississippians are divided over that choice: Governor Mabus won the nomination with just over 50 percent of the vote. His principal opponent, former United States Rep. Wayne Dowdy, received an unexpected 41 percent. While Mabus's percentages were high enough to guarantee that he'll be the Democratic nominee in the November election, they were low enough to prompt many political observers here to believe that the charismatic reform governor may be vulnerable. "He received the lowest percentage recorded for any Democratic nominee [for governor] in our state's history," says Ted Atkinson, communications director for the Republican Party of Mississippi. "We take it as evidence of his weakness with the voters. He's not nearly as popular as many people think." Equally troubling for Mabus was opponent Dowdy's refusal to endorse him for reelection after the primary vote. "Unquestionably, Mabus is going to have to unite the Democratic Party as much as he can, and get as many Dowdy supporters as he can, if he expects to have a fighting chance in November," says Stephen Shaeffer, a professor of political science at Mississippi State University in Starkville. Elected in 1987, Mabus has proved to be everything that isn't part of the nation's general image of a Mississippi politician: a Harvard Law School graduate, civil rights activist, and political reformer who has devoted a great deal of his first-term effort toward upgrading the state's education system. When Mabus was elected, he brought in dozens of young, energetic aides and government workers, creating an atmosphere that some likened to President John F. Kennedy's "Camelot." "For four years now, Mississippi voters have seen a young, energetic governor and his administration tackling old, stubborn problems," says Linda Crump, an assistant press secretary for the Mabus campaign. "They've liked what they've seen. Mabus is a reformer, he wants to change things for the better. And he's accomplished a lot of 'firsts' here." If Mabus is reelected in November, he will achieve yet another first: Because of a change in the state's one-term law for governors, Mabus would be the first incumbent to succeed himself. The governor will face either State Auditor Pete Johnson, a former Democrat, or Vicksburg businessman Kirk Fordice, a conservative Republican activist. Because neither Mr. Johnson nor Mr. Fordice received a majority of the Republican primary votes, the party must hold a run-off on Oct. 8. The outcome of that contest will shape Mabus's campaign strategy. "Fordice, for example, has taken some very conservative stands on many social issues," says Mr. Shaeffer. "So, against him Mabus will be able to emphasize his credentials as a progressive reformer. But if Johnson is the nominee, it may be tougher for Mabus, because Johnson is rather progressive, too, and he's very pro-education." Mabus also must run against recent Mississippi political trends. In the past three presidential elections, Mississippi voted decisively GOP. And both of its US senators are Republican. "This is a conservative state, and it's leaning more and more toward the Republicans," says Mr. Atkinson. "The Democrats have held the state house here for more than 100 years, and ... given the recent trends, their lock may soon be broken." Democrats, though, think the conservative trend in Mississippi may prove just as beneficial for Mabus. "First of all I'm not really sure that Mississippi is really all that conservative," says Ms. Crump, "because about 35 percent of the vote is black, and Mabus will win almost all of the black vote. But if there is a conservative trend, it's important to remember that Mabus has fought against any new taxes throughout his whole first term. And that's one thing any conservative likes to see."