Answer by taking a quote from the following article:

Edwin Washington Edwards (born August 7, 1927) is an American politician and member of the Democratic Party who served as the U.S. Representative for Louisiana's 7th congressional district from 1965 to 1972 and as the 50th Governor of Louisiana for four terms (1972-1980, 1984-1988 and 1992-1996), twice as many elected terms as any other Louisiana chief executive. He served a total of 16 years in office, the sixth-longest serving gubernatorial tenure in post-Constitutional U.S. history at 5,784 days. A colorful, powerful and legendary figure in Louisiana politics, Edwards, who has been dubbed the "very last of the line of New Deal Southern Democrats", was long dogged by charges of corruption. In 2001, he was found guilty of racketeering charges and sentenced to ten years in Federal prison.

As the 1991 governor's race drew near, many of Edwards' friends encouraged him to abandon his planned comeback, believing that he had no chance to win. After Edwards' loss in 1987, a journalist for the defunct Shreveport Journal wrote that the only way Edwin Edwards could ever be elected again was to run against Adolf Hitler. These words turned out to be shockingly prophetic, since after the 1991 primary Edwards discovered his runoff opponent to be former Imperial Wizard of the Ku Klux Klan, David Duke. Edwards received 34 percent of the vote while Duke received 32 percent. Governor Roemer placed third, 80,000 votes behind Duke.  The runoff between an avowed white supremacist and a former governor who was corrupt but was also perceived as minority-friendly, gained national attention. Support for Edwards grew in between the primary and the runoff. Louisiana Coalition against Racism and Nazism, an interest group, appeared to challenge Duke, with its leadership including longtime Treen supporter Beth Rickey, a member of the Louisiana Republican State Central Committee from New Orleans. The coalition revealed through a recording of Duke at a White Nationalist conference that he was still involved in Ku Klux Klan activities.  Faced with the alternative of Duke, many who were otherwise lukewarm for Edwards found him looking ever better. Edwards found himself receiving endorsements from Treen and Roemer; even Republican President George H. W. Bush urged that Edwards, the Democrat, be elected over Duke. A popular bumper sticker urging support for Edwards (although clearly not produced by his campaign) read "Vote For the Crook. It's Important." Another read "Vote for the Lizard, not the Wizard." Edwards said that this would be his final term as governor and that he cared about leaving a good legacy, which made many hope that the corruption of his previous administrations would not be repeated. Edwards won by a wide margin. Continuing his artful use of humor to deflate an opponent, and referring to his considerable reputation as a ladies' man, Edwards said of Duke that "the only thing we have in common is that we both have been wizards beneath the sheets." He also feigned concern for Duke's health due to smoke inhalation "because he's around so many burning crosses" and when a reporter asked Edwards what he needed to do to triumph over Duke, Edwards replied "stay alive." On Election Day, Edwards defeated Duke in a landslide, 61 to 39 percent, a margin of nearly 400,000 votes.

what happened in 1991?
As the 1991 governor's race drew near, many of Edwards' friends encouraged him to abandon his planned comeback, believing that he had no chance to win.