Sen. J. Bennett Johnston, D-La., won re-election to a fourth term in Louisiana's open primary Saturday, defeating former Ku Klux Klan leader David Duke, a Republican rejected by his own party because of his racist history.

With 91 percent of the vote counted, the unofficial returns showed Johnston leading with 667,481 votes, or 54 percent of the total, compared to 545,347 votes for Duke, or 44 percent of the total.The margin of victory was far less than the 60 to 65 percent Johnston had predicted earlier in the day but he still said it was a big victory.

"This is very clear. This ain't close," Johnston said. "I won this race by 10 full percentage points. That's a big win and I'm happy with it."

Duke said he would file suit to challenge the disallowance of absentee ballots cast for Ben Bagert, the Republican nominee who withdrew two days before the election. Duke said he would have gotten most of Bagert's votes if citizens who voted absentee for Bagert had another chance.

"We will fight to make sure their vote is heard in the state of Louisiana. . . We are not going to let a political deal determine the outcome of this election," Duke said. "Our preliminary indications are that Ben Bagert is drawing a number of votes, at least enough to make a difference."

Duke had charged Johnston cut a deal with Bagert to get him out of the race to prevent a runoff. When Bagert withdrew on Thursday, he said he was doing it because he knew he could not make a runoff and he did not want Duke to get in one.