Across the country, one of the main political stories of the season is about how, for the most part, mainstream Republican candidates focused on taking control of the U.S. Senate are holding tea party insurgents at bay.

In the recent Kentucky primary, U.S. Senate Minority Leader Mitch McConnell swatted away his GOP challenger. In North Carolina, establishment choice Thom Tillis won the right to face Democratic incumbent Kay Hagan, who, along with Louisiana’s Mary Landrieu and a handful of others, tops the GOP’s hit list for this fall.

For the next few days, many eyes will be on Mississippi, where longtime U.S. Sen. Thad Cochran faces an aggressive challenge from much younger, tea party-backed state Sen. Chris McDaniel. The contest for the GOP Senate nomination took a supremely weird turn in recent weeks when a blogger with ties to McDaniel entered the nursing home where Cochran’s wife, who suffers from dementia, lives and posted a photo of her.

Still, the race has the markings of a classic tea party-versus-establishment showdown. Cochran is an institution, but he’s spent 40 years in Washington working well with others — arguably too well, in the eyes of his critics. What’s worse, he made his mark as an appropriator.

Whether the mainstream is really winning the day or simply shifting to the right itself — the better to fend off those insurgents — is a whole other question. Honestly, you don’t see many major figures straying from conservative orthodoxy these days. Certainly not in Louisiana. And certainly not at party gatherings like the Republican Leadership Conference, which has been meeting over the weekend in New Orleans.

Louisiana’s Senate race has its own tea party-versus-establishment storyline, and it was on full display as Republicans gathered at the downtown Hilton. Retired Col. Rob Maness picked up the Tea Party Express endorsement and delivered a rousing, uncompromising stem-winder. Former Alaska Gov. Sarah Palin showed up to offer her live support; she declared him beholden to no machine, and compared him to tea party favorites such as Texas’ Ted Cruz and Utah’s Mike Lee (Palin is also backing McDaniel in Mississippi).

Down in the main hall, where delegates eagerly awaited a speech by “Duck Dynasty” patriarch Phil Robertson, state Rep. Paul Hollis got to make his pitch before what is surely the biggest audience of his campaign.

Both he and Maness are doing their best to stoke doubt that the leading Republican in the field to replace Landrieu, U.S. Rep. Bill Cassidy, is a true enough believer — based not so much on his recent record, which is self-consciously conservative, as on his past backing for health care reform measures similar to the Affordable Care Act and for, yes, Landrieu herself.

There was good news for Cassidy, too, last week. His campaign picked up a few of its own big-name conservative backers, former House Speaker Newt Gingrich and Texas Gov. Rick Perry. U.S. Sen. David Vitter, who has long been a behind-the-scenes presence in the Cassidy campaign, also recently issued an overt endorsement. Gov. Bobby Jindal, meanwhile, is remaining characteristically hands-off. All he had to say in a question-and-answer session after his own RLC speech is that he wants to see Landrieu’s seat switch to the GOP column.

If Louisiana’s Republican fight is shaping up like the ones in other states, there are some key differences, all of which favor Cassidy. Where tea party Republicans have broken through, it’s been in straight all-GOP primaries, the kind Louisiana abandoned a few years back. By the time Republicans here get to weigh in on Election Day in November, the question that will eclipse all others is whether Landrieu can be toppled and whether the Republicans can win back control of the Senate.

It will be a complicated time for Cassidy, who will have to appeal simultaneously to conservatives who might otherwise go for Maness or Hollis, as well as moderates deciding between him and Landrieu. That’s the downside for him. The upside is that, by then, the whole establishment-versus-tea party dynamic may well be played out. And even if Maness and Hollis peel off enough votes to force a Cassidy/Landrieu runoff, he should attract his rivals’ supporters.

What else are they going to do, sit back and help Landrieu win?

Stephanie Grace can be contacted at Read her blog at http://blogs.the Follow her on Twitter @stephgracenola.