Louisiana Republicans packed into a small bar named after one of the state’s most notorious Democrats on Monday to rally around U.S. Rep. Bill Cassidy’s effort to unseat Democratic U.S. Sen. Mary Landrieu.

The irony of the GOP’s top Louisiana politicians meeting with hundreds of raucous supporters in “Huey’s” bar — yes, as in Huey P. Long — wasn’t lost on the attendees.

“Huey Long was the last person in Louisiana to beat an incumbent U.S. Senator,” Cassidy said. “He was the last, and we’ll be the next.”

U.S. Sen. David Vitter, a Republican who has been campaigning for Cassidy, said the venue appropriately reflected the state’s switch from Democratic to Republican domination.

Landrieu, who faces Cassidy in a Dec. 6 runoff, is the only remaining statewide Democrat officeholder.

“It’s great to be in Huey’s — chock-full of Republicans,” Vitter said. “We’re changing Louisiana politics.”

Landrieu narrowly came out on top in Tuesday’s vote tally — besting Cassidy by about 16,000 votes — but didn’t pull in enough votes to avoid the runoff. Republican political novice Rob Maness, who had built up a vocal far-right coalition of supporters in the primary, took more than 200,000 votes and has since endorsed Cassidy.

Monday’s event appeared especially targeted at wooing those Maness voters. It was billed as a “unity rally,” and much of the crowd responded enthusiastically to Maness’ appearance.

Cassidy’s speech touched on several popular red-meat topics — the federal Affordable Care Act, Environmental Protection Agency regulations and energy policy among them.

“People across the state are coming together because they realize that Mary Landrieu no longer represents Louisiana, she represents Barack Obama and his failed polices,” Cassidy said.

“The only thing I fear is that we are overconfident,” Cassidy later added.

Most polls indicate that Cassidy’s in the lead in next month’s runoff, but Landrieu’s campaign is mounting its own offensive, despite the Democratic Senatorial Campaign Committee’s decision to back off efforts in the race — starting with a new television ad that calls Cassidy “nearly incoherent” while splicing together several flubs from a nine-minute speech he gave in May at the Republican Leadership Conference.

The ad, which aired during the New Orleans Saints game broadcast Sunday, shows Cassidy stuttering and tripping over his words as the voice over asks if Louisiana should “lose Mary Landrieu’s clout ... for this?”

The Democrats have launched several new websites targeting Cassidy — WhereWasBill.com to question his leadership for Louisiana and RealBillCassidy.com, which includes footage of what it calls an “awkward” election night speech from Cassidy.

The Landrieu campaign on Monday also touted an influx of online donations from supporters — $400,000 in the first five days of the runoff campaign.

“Sen. Landrieu’s supporters are proudly standing by her side in the runoff election, and we are confident, with this outpouring of support, we will be able to celebrate a victory on Dec. 6,” Landrieu campaign spokesman Fabien Levy said in a statement.

But the over-arching message from the Republican event in Baton Rouge on Tuesday: The far-right “tea party” brand of Republicans are ready to embrace Cassidy — previously seen as an “establishment” GOP candidate. And that’s likely just what he needs to push him over the edge.

Kentucky U.S. Sen. Rand Paul, a tea party favorite, was the featured guest and an obvious draw to the crowd.

He said Republicans winning control of the U.S. Senate last week was a direct response to Obama. “This election was a repudiation of the president and his policies,” Paul said.

He said he struggled between support for Cassidy or Maness in the primary. He endorsed Cassidy after the primary and after speaking to Maness, he said. “I believe Bill Cassidy will defend the Constitution,” Paul said.

Many of the attendees were dressed in red, white and blue. Supporters cheered for Cassidy and booed loudly whenever Landrieu or Obama were mentioned. They waved signs that riffed on Landrieu’s “I’m with Mary” slogan with the words Bill Cassidy “He’s with You” on them.

Maness, in particular, offered full-throated support for Cassidy, just a week after he failed to secure enough votes to face Landrieu in the runoff himself.

“I’m ready to hit the road whenever (Cassidy) needs me to,” Maness said.

Sarah Palin, the former vice presidential nominee who had previously endorsed Maness in the race, will be in Louisiana on Saturday to stump for Cassidy.

In addition to Maness, Cassidy and Vitter, the event drew Gov. Bobby Jindal, state Sen. Elbert Guillory, state Rep. Paul Hollis and former Congressman Jeff Landry.

Jindal, who also didn’t endorse a candidate until after Tuesday’s primary, compared Cassidy’s momentum heading into the final weeks of the election to the LSU and Saints losses in overtime over the weekend. He said he thinks Cassidy will win, but he doesn’t want to take it for granted.

“The only call that counts is what happens on Election Day,” Jindal said. “The eyes of the nation are on Louisiana.”

Follow Elizabeth Crisp on Twitter, @elizabethcrisp. For more coverage of Louisiana politics, follow our Politics blog at http://blogs.theadvocate.com/politicsblog.