Though U.S. Sen. Mary Landrieu had a distressing week on the campaign trail with a major shake-up of her campaign staff, Republican challenger Bill Cassidy had some challenges, too.

A Time magazine blog called him a “virtual candidate,” a description conservative icon Rush Limbaugh repeated on his national radio program.

Landrieu’s campaign described Cassidy’s unwillingness to debate as “chronic cowardice,” and her operatives called for the Baton Rouge congressman to “man up.” Landrieu added, “I don’t look that scary.”

All of this refers to Cassidy ducking debates and joint appearances. His handlers have had trouble notifying everyone of public campaign events. But they have been sticklers when it came to limiting access.

Back on Aug. 20, Cassidy couldn’t say where he would be two hours later: A high school football game, Natchitoches, maybe? Could be Monroe, somewhere up north. “I’m new at this,” Cassidy shrugged during a conversation last week.

Cassidy disputes claims that he has been running a stealth campaign but said he personally would make sure that all his appearances are well-advertised in advance from here on.

He also said two debates were plenty. “How many times do we need to go over the point that she has voted with President Obama 97 percent of the time?” he asked.

Tuesday will be the first debate Cassidy participates in with Landrieu and Rob Maness, the Republican candidate with the backing of tea parties.

Cassidy is the lead GOP candidate challenging the last Democrat elected statewide in a state where President Barack Obama’s popularity continues to plummet.

So, the biggest thing going for Cassidy, in the view of most observers, is the R behind his name. And his best route to victory is to not make any mistakes.

The days of candidates wandering through festivals and greeting all comers is pretty much over.

Bobby Jindal and David Vitter showed that a candidate could win Louisiana with pithy commercials, bumper sticker slogans, seeming insider access via social media and limiting public appearances to controlled situations.

But Cassidy’s photo-ops don’t always produce the same cheery images so treasured by political campaigns.

Last week, surrounded by aides filming everything he did, Cassidy visibly fought back crying on camera while listening to a mother describe her struggle with her dyslexic son’s self-esteem.

Run into Cassidy shopping, which he usually does without his entourage in tow, and the off-the-cuff conversation reveals someone who studies issues carefully and can articulate reasons for his positions that don’t sound like they come from a “talking points memo.” He even enjoys the thrust and parry of opposing views.

That’s the kind of depth that often gets candidates in trouble. Cassidy agrees that his refined points are often taken out of context and show up in the ads attacking him. (In fairness, Cassidy’s supporters do the same thing to Landrieu.)

On the stump, Cassidy comes off a little like Zeppo, the non-zany Marx Brother.

Speaking to the Associated Builders & Contractors Inc. last week, he struck a professorial air, enunciating carefully with lots of hand gestures. This was a presumably “friendly” crowd, given the number of members who have donated to the Cassidy campaign and the tee-ball questions asked of the candidate.

Cassidy stuck with the accepted GOP theme that anything Obama does is bad for Louisiana. The few times Cassidy referred to Landrieu, it was in context of Obama.

As chairman of the U.S. Senate Energy and Natural Resources Committee, he pointed out, Landrieu was unable to get a floor vote on any pro-energy legislation because the Senate is controlled by Obama Democrats.

“Karl Rove thinks whichever party wins Louisiana will control the U.S. Senate. Wow,” Cassidy said in his speech. “It is up to us. We in this room will decide, we will contribute to which party controls. … We will be judged by history.”

Of course, that neglects the fact that in two years, the stars will align in such a way that Democrats have the better chance of picking up enough seats to win back control of the U.S. Senate.

Landrieu also is no slouch in terms of study and understanding of issues.

But this debate in Shreveport on Tuesday is not going to be any textured discussion on issues. It’s going to be about whether the chairmanship of the Senate energy committee is more important than having a Republican majority in both houses of Congress.

Mark Ballard is editor of The Advocate Capitol news bureau. His email address is mballard@theadvocate.com. Follow him on Twitter, @markballardcnb.