The first televised debate of Louisiana’s vigorously contested U.S. Senate campaign was one of the stranger showdowns you’re likely to see, what with the conspicuous absence of the guy who has at least an even shot at becoming the state’s next senator.

Moderator and WDSU anchor Scott Walker told the audience at Thursday’s taping that “despite several pleas,” Republican U.S. Rep. Bill Cassidy had turned the station down. Cassidy is set to participate in just two debates, starting with Tuesday’s forum on Louisiana Public Broadcasting, while Democratic U.S. Sen. Mary Landrieu and tea party Republican Rob Maness pushed for five.

Yet the show went on as planned, and the friendly but feisty exchange between Cassidy’s two rivals easily disproved his contention that debates are merely “highly scripted” affairs.

The far more credible reason behind Cassidy’s reluctance, as well as his rivals’ eager participation, is how much each has to win or lose at this late stage.

Cassidy is playing it safe because he can and arguably should. His party ID, in a Republican state and a Republican year, may be enough to get him across the finish line, and he clearly doesn’t want to make any mistakes or expose himself to in-person attacks, which in this case would come from both left and right. It’s a tactic more often employed by incumbents or well-established frontrunners, and it makes some sense strategically, even if it’s frustrating for those who want to hear from him or see how he’d handle himself in, yes, an unscripted conversation with two pretty tough customers.

In an odd role-reversal, the candidate who approached the debate like an underdog was the sitting senator. Landrieu took repeated, unanswered swipes at Cassidy. Some were indirect, like when she thanked Maness for showing up and noted that “I think debates are important for democracies.” Some were on the nose, like when she linked Cassidy’s opposition to Medicaid expansion and a higher minimum wage to unpopular Gov. Bobby Jindal.

More interesting was how Landrieu positioned herself on issues.

She didn’t act like a Republican-lite, or soft-pedal party-line votes on which she’s sided with the Democrats, as she sometimes awkwardly does. Instead, she owned her advocacy for equal pay laws for women and a higher minimum wage for all (a change that would disproportionately help households headed by women, she contended) and for birth control insurance coverage for employees of private, nonreligious businesses whose owners object.

Asked about the Affordable Care Act, Landrieu was strikingly unapologetic. While she noted that it’s not perfect, she spent most of her answer listing the many popular benefits that would disappear if it’s repealed, including coverage for pre-existing conditions and coverage of young adults under their parents’ plans. Both GOP candidates propose overturning the law.

On immigration, she noted that she’d backed hiring more agents and building a fence but also defended her support for a path to citizenship for illegal immigrants who’ve made their home in the U.S. for years.

“You can’t deport 12 million people,” she said.

It’s probably no accident that the shift in tone came after a late-inning campaign shake-up. Landrieu’s new campaign manager ran her brother Mitch’s mayoral campaign, and the team’s current focus seems to be less on appeasing those who worry about the Senate’s partisan balance — in this environment, they’re not going to back a Democrat anyway — than on turning out voters who comprise her natural base, including women, Democrats and New Orleanians.

Like Landrieu, Rob Maness appeared thrilled to be onstage. He didn’t go after Cassidy as much as he might have, sticking mainly to general criticisms of career politicians. Instead, he basked in the one-on-one with the sitting senator and frequently contrasted himself with Landrieu.

“Let me be clear,” he said after she answered the immigration question. “No amnesty. No pathways to citizenship.”

Maness also offered an occasional variation on the small-government theme, like when he rejected a national minimum wage hike but said he’d be open to state-level increases. And while he had a few eloquent Reaganesque moments, he also made a couple of rookie mistakes. Asked about the Citizens United Supreme Court decision that opened the floodgates for big corporate money in politics, Maness said it was that decision that enabled him to run.

Not so, Landrieu interjected, pointing out that Maness’ contributions have come from small donors. Good for him, she said, before using the exchange to tee up another shot at their mutual nemesis.

“All those big corporations,” Landrieu said, “are supporting the guy who’s not here tonight.”

Stephanie Grace can be contacted at sgrace@theadvocate.com. Read her blog at http://www.theneworleansadvocate.com/news/politics/10436531-123/sen-landrieu-attacks-cassidy-forhttp://theadvocate.com/news/10478110-123/mary-landrieu-shakes-up-herhttp://theadvocate.com/news/acadiana/10435092-123/stephanie-grace-landrieu-republicans-thinnermailto:sgrace%40theadvocate.com?subject=http://blogs.theadvocate.com/gracenotes">http://blogs.theadvocate.com/gracenotes.