COULD it really happen? Could David Duke, a former imperial wizard of the Ku Klux Klan, be on the verge of winning the governorship of Louisiana?Mr. Duke, founder of the National Association for the Advancement of White People, has pulled within four points of the front-runner, former Gov. Edwin Edwards. Experts call the outcome a tossup. "This has the prospect of being a very close election," says Democratic pollster Geoffrey Garin, who has conducted extensive surveys in Louisiana. "People who don't take the possibility of a Duke victory seriously ought to think again." Other political analysts, speaking anonymously, say they now expect Duke to win the Nov. 16 contest, although narrowly. A Duke triumph, laced with racial overtones, would send a shock wave through American politics, and could prove embarrassing to both the Republican Party and President Bush. Duke calls himself a Republican. But his reputation - he once paraded in a Nazi uniform, for example - conjures up images of bigotry and demagogery. Even so, his message, attacking welfare handouts, minority set-asides, and illegitimate births, stirs some white voters. Wayne Parent, a political scientist at Louisiana State University, says Duke's excellent prospects are something of a fluke. Ordinarily, he would be far behind because he is extremely unpopular with most Louisiana voters. A just-released Mason-Dixon poll, for example, found that 54 percent of the voters say they would never vote for Duke under any circumstances. Yet Duke still has a chance because his opponent, Mr. Edwards, is even more unpopular with many Louisianans. In the 1980s, Edwards was tried on racketeering charges, but eventually was acquitted. Analysts say many citizens, disgusted by either choice, will sit out the election. Others will vote for the one they dislike the least. Tim Gallagher, a vice president at Mason-Dixon, says the outcome rests with undecided voters, most of whom cast ballots for the current governor, Buddy Roemer, in the primary. Mr. Roemer finished third in that contest. Mason-Dixon found that among undecided voters, 70 percent feel that Edwards's past is even worse than Duke's; 58 percent believe Duke is more trustworthy and honest. Dr. Parent says he is "stunned" by those numbers from Mason-Dixon, and he blames the White House for softening public attitudes toward the kind of racism that Duke expresses. Republican appeals to subtle racism, as expressed in the famous Willie Horton ad for the Bush campaign in 1988, have cleared the way for demagogues, Parent says. "The foundation [for Duke's campaign] was laid by [Ronald] Reagan and Bush," Parent charges. "All of a sudden it was all right for the South to be racially divided. Reagan's and Bush's appeal to Southerners was tacitly and subtly racist. "Some down here have been appalled for 10 years at [the Republicans'] racially tinged arguments. In the short run it helps politically, but in the long run it comes back to haunt you. Reagan and Bush helped make this situation possible," he says. A number of Democrats, such as Louisiana party chairman Jim Brady, say there are two things that could still defeat Duke. One of those would be a strong statement from Bush, preferably one which embraced Democrat Edwards for the job. Bush already has gone part-way toward doing that. At a press conference on Oct. 25, he said: "I could not possibly support David Duke because of the racism and because of the very recent statements that are very troubling in terms of bigotry." When Bush was pressed by reporters to go further, however, the president responded: m not going to inject myself in here, except to say that we can never in any way support David Duke.... So please don't try to draw me into a runoff in that state. I'm not going to be so drawn." That upsets some Democrats. Pollster Garin, for example, says: "George Bush has a crucial role to play in whether or not David Duke becomes the next governor of Louisiana." Garin explains that most of the undecided voters in this race are Republicans - upscale, well-educated Republicans. "They are the type of people who like George Bush and respect him. Bush's 'silence' thus far, I think, has been deafening," he charges. The economy could be an even more important factor, however. As Parent explains, people in Louisiana wonder "whether we'll become a leper colony" in the eyes of the rest of the country if Duke wins. Democrats plan to play on those concerns. State chairman Brady says: "The voters understand that they cannot afford to take the economic hit that the election of David Duke will present to this state." Brady says that businessmen, convention planners, and others across the country have already decided that "if David Duke is elected governor ... they're not going to be expanding into the state. Convention business, which is a great source of revenue for our state, could dry up." Yet Democrats know Edwards has serious problems. Edwards, who still speaks with the Cajun accents of Crowley, La., where he first won political office, was a popular governor in the 1970s. Barred from a third consecutive term by the state constitution, he bided his time, then came roaring back in 1983 with 63 percent of the vote over incumbent Gov. Dave Treen. Shortly afterward, however, he was indicted by a federal grand jury under the Racketeer Influenced Corrupt Organizations Act. In 1986, Edwards won an acquittal, but his popularity was punctured. As Parent observes: "It was like a great romance that went bad." So disliked is Edwards today that Duke leads him among white voters by a 58 to 25 percent margin, according to Mason-Dixon. His unfavorable rating among whites is 62 percent. That puts the heat back on Bush. Perhaps the only way the prevent Duke's election would be for Bush to throw his arms around Edwards, a gesture no Republican would relish.