Among Louisiana’s battered Democrats, there are two ways of interpreting Mary Landrieu’s loss to Republican Bill Cassidy in last weekend’s Senate election — a blowout that marks the complete disappearance of Democrats from statewide elected office in Louisiana.

From one point of view, Landrieu’s defeat is a one-off phenomenon: Her opponent, backed by an unprecedented amount of campaign spending by outside groups, tied the incumbent to an unpopular president with a relentless advertising blitz.

From this perspective, neither the Democratic Party nor the Landrieu brand should be written off. Mayor Mitch Landrieu, Mary’s brother, has built a reputation as a turnaround artist at City Hall in New Orleans, and the next governor’s race could be framed more as a referendum on Gov. Bobby Jindal — a Republican with lousy approval ratings — than on President Barack Obama.

“It’s hard to imagine that the political climate for a state election in 2015 is going to be the same as in a federal election in 2014,” said James Carville, the liberal pundit and campaign strategist who has been one of the mayor’s biggest boosters.

The opposite theory about Mary Landrieu’s defeat goes like this: The Republican tide that began sweeping the Deep South in the 1960s has finally drowned its last victim. Republicans will own the place for a generation, and Democrats are better off trying to take on the role of arbiter between competing Republican factions than putting resources behind doomed candidates.

If that’s true, it could put a ceiling on Mitch Landrieu’s political aspirations and mean the end of a political dynasty that began with his father Moon Landrieu’s two terms as New Orleans mayor in the 1970s.

“These types of shifts take generations,” said University of New Orleans professor Ed Chervenak, who leans toward the second interpretation. “Think of how long it took Republicans to take over.”

People close to the mayor’s camp certainly are not writing off the idea that Democrats could move past his sister’s defeat and capture statewide offices again in the near future. Nor do they rule out the possibility that the mayor could run for governor next year.

“I think he would consider it,” said Greg Rigamer, a demographer who worked for Mitch Landrieu’s successful re-election campaign and insists that “the right Democrat could be competitive.”

In Rigamer’s view, black voters in Louisiana, who still vote overwhelmingly for Democrats, are more or less canceled out by those who always vote Republican. But there is still a solid third of the electorate — white registered Democrats and independents — to wage a battle for, even if that group has become more conservative over time.

“Clearly, it’s not a good day to be a Democrat in Louisiana. I’m not suggesting things are fine,” Rigamer said. “But you’re going to have a different dynamic in the governor’s race.”

One Democratic Party insider, who asked not to be identified discussing strategy so far from the election, argued that a strong Democratic candidate could make an effective, populist case against the Republican status quo by attacking Jindal over cuts to higher education and health care.

“I think people remember a day when our universities were funded and health care wasn’t being dismantled,” he said. “When the debate is not so focused on the national message machine going, ‘Barack Obama, Barack Obama, Barack Obama,’ then someone has a chance to cut through.”

Another thing Democrats point out is that Mitch Landrieu has time to make up his mind. Unlike state Rep. John Bel Edwards, a Democrat from Amite who already has announced for governor and is widely considered a long shot, the mayor won’t need to spend time or money just building a public profile outside of his home base. He was twice elected to lieutenant governor, a statewide post.

So Landrieu could decide relatively late in the game — just as he did before his successful run for mayor in 2010 — and become a factor immediately.

Still, others think all this needs a reality check.

Chervenak, the UNO professor, argues that conditions may not be so different for Democrats during the next statewide election than they were in the most recent one. “As long as Obama is in office, there’s going to be a lot of hostility toward Democrats in this state,” he said. “With all this outside money coming in, even a governor’s race may be nationalized.”

In this view, Mary Landrieu’s loss was the result of trends that have been playing out for decades and only accelerated recently: the drift toward Republicans in the South and the growth of a national debate — fueled by the opposite poles of Fox News and MSNBC — in which ideology trumps bread-and-butter issues.

Landrieu tried to win a fourth term by pointing out the federal dollars she had brought home to Louisiana and highlighting her loyalty to the oil and gas industry. But she was easily outdone by an opponent who successfully made the race about the Affordable Care Act, aka “Obamacare,” and immigration policy.

And it’s not just Mary Landrieu who has suffered. There are nine statewide elected offices in Louisiana. As recently as 2003, Democrats held eight of them. Now, they have none.

Even Forest Bradley Wright, an obscure candidate who jumped to the Republican Party to run for a seat on the Public Service Commission, got targeted during the campaign as a closet Obama ally in television ads. He drew the most ballots in the first round of voting but lost to Republican Eric Skrmetta in the runoff.

It is easy to imagine Mitch Landrieu getting attacked along similar lines in a statewide race, having pushed tax increases in Orleans Parish and having criticized the governor for not accepting an expansion of Medicaid in Louisiana as a part of the president’s health care overhaul.

Pearson Cross, an associate professor of political science at the University of Louisiana at Lafayette, said Democrats probably have lost most of the white vote in Louisiana for at least the next 10 or 15 years, until a younger generation comes along. Mary Landrieu’s share of the white vote dropped to just 18 percent in the November primary. She got nearly a third when she beat Republican John Kennedy for a third term in 2008 — the most decisive of her three victorious Senate campaigns.

Pearson said the only hope for Democrats would be a wholesale reversal of that trend, which he could imagine coming to pass in Louisiana only as a result of “corruption or scandal.”

Even some of those who are sorry to see the Landrieu dynasty fade think the state’s Democratic Party will need time to rebuild.

“If I were advising him, I’d say let it go,” as far as the governor’s race, said Jason Berry, a New Orleans-based reporter and author who has written extensively about the Catholic church.

“From Moon to Mary to Mitch, the Landrieus have had remarkable impact on this city and state,” Berry said, suggesting that Mitch Landrieu should see out his second term as mayor, focus on the city’s tricentennial celebration in 2018 and then start to weigh his options.

“There’s going to be enormous media coverage, most of it is going to be favorable, and he’s going to be on a roll,” Berry said. “Even if he takes a year or two off, suppose he decides to run against Cassidy in six years? Time is on his side.”

Editor’s note: This story was changed on Dec. 15 to correctly identify author Jason Berry.