The candidates for the U.S. Senate are making last-minute appeals to voters this weekend with their final TV ads and campaign appearances throughout the state, especially in voter-rich south Louisiana, in a primary election that’s too close to call.

Polls indicate that state Treasurer John Kennedy, a Republican from Madisonville, has the best shot at winning one of the two spots in the month-long runoff that will begin immediately after Tuesday’s primary election.

But, with private polls showing a variety of results, four other candidates are making the case that he or she will make the runoff. Those candidates are two Republicans — U.S. Rep. John Fleming, of Minden, and U.S. Rep. Charles Boustany, of Lafayette — and two Democrats — attorney Caroline Fayard, of New Orleans, and Foster Campbell, a member of the elected Public Service Commission from Bossier Parish.

Given Louisiana’s jungle primary, where the top two finishers make the runoff regardless of party affiliation, any two-person combination involving the five candidates is plausible, although it’s highly unlikely that both Democrats will advance.

Another 19 candidates are on Tuesday’s Senate ballot, including former state representative and Ku Klux Klan grand wizard David Duke, of Mandeville, and retired Air Force Colonel Rob Maness, of Madisonville. Both are Republicans.

Duke got a burst of publicity over the past two weeks by qualifying for and becoming the center of attention during Wednesday night’s raucous televised debate at Dillard University. But his unpopularity among voters is so high that few people other than Duke say he will make the runoff.

Maness has delivered a consistent, conservative message, but he failed to qualify for either of the two televised debates, indicating his limited viability.

The winner of the Dec. 10 runoff will replace Sen. David Vitter, R-Metairie, who chose not to seek a third term after losing last year’s governor’s race.

Besides a senator, voters will elect a new president, their U.S. House representative and vote on six constitutional amendments. Voters in 38 of the state’s 64 parishes will decide local ballot propositions — mostly whether to approve or renew taxes.

For the election, the Secretary of State’s Office is forecasting a 68 or 69 percent turnout of registered voters, which would be a slight increase above the 67.9 percent rate in 2012 and 67.2 percent rate in 2008, according to spokeswoman Meg Casper. The expected turnout figure would have about 2 million voters in Louisiana casting ballots.

Record numbers of voters turned out for the one-week early voting period or have sent in absentee ballots, but Casper said 98 percent of them are so-called chronic voters. This suggests an overall jump in voting this year is unlikely.

“I think more people know about early voting,” Casper said. “They like the convenience. We also think some of the flood victims took advantage of early voting.”

All of the major candidates have people calling likely supporters to get them to show up Tuesday and in the final days are planning to visit African-American churches (in the case of Fayard and Campbell) or anywhere else they hope to find friendly faces, including Saturday night’s LSU-Alabama football game.

The Senate candidates are coming off of Wednesday night’s debate in which Fayard attacked Duke, Campbell attacked Fayard, Fleming attacked Kennedy, Duke attacked Kennedy and countered Fayard and Kennedy counterattacked Duke and Fleming. Boustany stayed out of the fights.

About 53,000 people watched the debate in the New Orleans media market according to Vicki Zimmerman, the regional news director for Raycom Media, the debate organizer, in the only figures available Friday.

Kennedy is making his ninth race for statewide office, having won five elections to be treasurer, lost one to be attorney general and lost two to be senator.

He is closing this campaign with an ad where he looks into the camera and promises never to support a new tax, undoubtedly a popular view with voters but one that would limit his decision-making options if he wins.

“You either believe that the Washington insiders have done a good job for America, or you don’t,” Kennedy said in an interview. “If you do believe that we can do better, I’m your guy.”

Boustany, who has served Acadiana in Congress since 2005, is touting endorsements from Jefferson Parish Sheriff Newell Normand, a slew of state legislators and such newspapers as Gambit, The Times-Picayune and The Daily Advertiser. (The Advocate does not endorse candidates.)

Boustany is running two ads, one that mocks Kennedy as a publicity hound and another that touts his background as a heart surgeon who knows how to handle serious problems.

“All of the shouting and screaming and hot air in Washington is not solving problems,” said campaign spokesman Jack Pandol. “Dr. Boustany is the proven problem-solver.”

Fleming, who has represented northwest Louisiana in Congress since 2009, is broadcasting an ad in which viewers see a brief clip of Donald Trump saying that the system is “rigged” and Fleming then explaining why Trump is right.

“We’re staying positive,” said campaign spokesman Matt Beynon. “Louisiana voters are getting sick of all the negativity.”

The negativity continues to come from a super PAC funded by Kennedy that is headed by Kyle Ruckert, formerly the top aide to Vitter. The super PAC is attacking both Fleming and Boustany.

One early-voting statistic has caught the attention of political insiders: African-Americans have represented only 26.6 percent of early voters this year versus 33.3 percent in 2012. A drop-off in African-American turnout through Election Day could allow Republicans to win both runoff spots.

Here’s why the African-American turnout is so important to Campbell and Fayard — African-Americans will account for about 75 percent of the votes that Democratic candidates receive in the primary, with whites now voting overwhelmingly for Republicans in Louisiana, said demographer John Couvillon who has polled for Fleming.

In the 2014 Senate primary, Mary Landrieu won about 22 percent of the white vote — a good yardstick for what to expect in Tuesday’s Senate primary.

Either Campbell or Fayard seems assured of making the runoff if either wins at least 60 percent of the African-American vote on Tuesday. A 50-50 split in the African-American vote could keep both from advancing.

That African-Americans will provide most of the votes for the Democratic candidates Tuesday explains why Fayard broadcast a TV ad in New Orleans and Baton Rouge that took audio of a Campbell statement out of context to link him to Duke.

It also explains why Campbell launched a ferocious counterattack where, at Wednesday night’s debate, he said, “It’s not just a lie, it’s a damn lie,” and released statements from prominent African-American political leaders slamming Fayard for the spot. Gov. John Bel Edwards, who is supporting Campbell, also condemned the commercial.

Fayard has replaced the spot with one where she says unidentified “good old boys” didn’t want her to run and promises to work for equal pay for women, a “living” wage for workers and coastal restoration.

“Elections are fundamentally about the future and not the past,” spokesman Beau Tidwell said Friday, “and Caroline is running to offer not just a new generation of leadership but a new kind of leader.”

As Tidwell’s comments indicate, the Fayard campaign is playing up her relative youth and political inexperience as an advantage. Fayard is a 38-year-old attorney in New Orleans who has never held elected office while Campbell, 69, lives on a farm in Bossier Parish and has been a state senator or elected utility regulator since 1976.

Campbell puts his age and experience in a positive light in his latest ad where he says, “The United States Senate is no place for beginners.” Demonstrating the importance of these issues for Democrats, Campbell in his ad also calls for equal pay for women and a higher minimum wage.

Political insiders give Campbell the edge in getting his supporters to the polls on Tuesday. He has the endorsement from the AFL-CIO, which is pushing its members to vote for him.

State Rep. Terry Landry, D-New Iberia; state Rep. Jeff Hall, D-Alexandria; state Rep. Cedric Glover, D-Shreveport; state Rep. Kenny Cox, D-Mansfield; and state Rep. Marcus Hunter, D-Monroe — members of the Black Legislative Caucus — said in interviews that they are asking their supporters to vote for Campbell, as are several African-American political groups in New Orleans, including BOLD, COUP, TIPS, the Algiers Political Action Committee and the New Orleans East League.

“We have an organized effort based on the platform we built for state House elections in 2011 and for John Bel Edwards’ campaign last year,” said Eric Foglesong, Campbell’s campaign manager.

Fayard is countering with the political team associated with New Orleans Mayor Mitch Landrieu and his sister Mary. Both have endorsed her.

Follow Tyler Bridges on Twitter, @tegbridges.