The final debate of Louisiana U.S. Senate primary campaign was effectively two debates in one.

The first featured the five candidates who have been atop the polls for months now, each jockeying for one of two runoff slots.

The second, of course, focused on a sixth candidate, a fringe figure who has no shot at winning but who snuck in based on sponsor Raycom Media's decision to issue invitations according to results from its own poll. Former Ku Klux Klan Grand Wizard David Duke scored just over the five percent cutoff for the only time in this season, and as many feared, his presence on stage — at historically black Dillard University in New Orleans, no less — proved an epic distraction.

The others did their best to stay on point, particularly the three Republicans. U.S. Rep. Charles Boustany, the wonkiest of the trio, showed his usual ease with the details of policy.

His congressional colleague John Fleming focused on knocking support off the frontrunner in most polls, state Treasurer John Kennedy, in the hopes the voters might shift to him. His attacks centered on Kennedy's past membership in the Democratic Party and his stewardship in Louisiana. "If you were my chief financial officer, you would have been fired a long time ago," he said at one point.

Kennedy, meanwhile, rattled off the names of other Republicans who used to be Democrats, including presidential nominee Donald Trump, and labeled Fleming a Washington insider.

The two Democrats stayed focused on one another too, with much of the heated back-and-forth directed at lawyer Caroline Fayard's misleading ad attempting to link Public Service Commissioner Foster Campbell to Duke, who was standing between the two on stage. At one point, Fayard likened Duke to a slithering snake, and Duke chimed in with a request to rebut. That tells you a lot about how the night went down.

WVUE's John Snell is probably the most seasoned and talented debate moderator Louisiana has, but this still went off the rails. Early on, he got into a shouting match with Duke, and in general saw his pleas that the debate not be turned into a "referendum on one candidate" at least partially ignored.

Since Duke was front and center, though, Snell probably felt like he had to push him on his record of bigotry, and he did so by asking why Duke criticized coverage of Trump and Billy Bush's infamously offensive hot mic conversation by singling out "the CNN Jews." Duke responded by insisting "there is a problem with a very strong powerful tribal group" that dominates media and banking.

Towards the end, Snell said time was running short and rushed candidates through a potentially revealing question about the Supreme Court — so much so that poor Campbell got cut off just as he was working his way up to his answer — in order to get to closings. Only then did he realize he had extra time to kill. In all, the evening was far short of illuminating, which really wasn't fair to the other candidates trying to make a final impression, and especially to the voters who wanted to hear substance.

When it was over, WYES, the New Orleans public television station that aired the debate as Raycom's WVUE showed the World Series, cut to video and audio of a soothing water fountain. It was too little, too late.

Follow Stephanie Grace on Twitter, @stephgracela.