Nikki Haley enters her YOLO stage

Artie Walker Jr./AP

Nikki Haley has entered her YOLO stage.

The last of Donald Trump’s rivals in the GOP primary, Haley is unloading on the former president — proceeding without any real caution for the first time in her campaign.

She’s taking repeated, pointed, shots at an “unhinged” Trump’s mental fitness and legal problems. She’s taunting him to debate her: “Show me what you got.” In recent days, her campaign responded to an 815-word memo from Trump’s advisers — a document arguing Haley is toast — with a “Why are you so obsessed with us?” meme from “Mean Girls.”

Then, Haley’s campaign said it was starting a new series of online ads called “Grumpy Old Men” — photoshopping the faces of Trump and President Joe Biden onto a movie poster from the 1993 film of the same name.

Few, if any, believe it will work. And Haley’s let-’er-rip approach comes with serious risk. Attacking Trump so frontally could create a long-term branding problem for her. Already, the MAGA-dominated GOP has accused her of treachery. Trump allies say she’s effectively burned her career in Republican politics.

But Haley seems to have concluded that freedom is just another word for trailing by 20-plus points.

“It’s very clear she’s got to differentiate. It’s deliberate,” said Vikram Mansharamani, who co-chaired Haley’s campaign in New Hampshire. “It’s sort of a requirement at this stage."

And in a primary largely sapped of serious competition — and for months, any sense of excitement — Haley, at least, appears to be having a good time.

Following her “Grumpy Old Men” ad, Haley posted on X, formerly known as Twitter, a photo of a Halloween costume featuring Trump on the package, calling the outfit “Weakest General Election Candidate Ever.” Not long after, she was on CNN accusing Trump of not being able to afford to hold campaign rallies. Then, over the weekend, she went on “Saturday Night Live” to troll him, appearing as a “concerned South Carolina voter” who wanted to ask Trump a question.

Those who have waited for a Republican candidate to go one-on-one with Trump have been delighted to see Haley seize the moment. Others say she is entitled to make the most aggressive case she can for the nomination.

Shawn Steel, the RNC committee member from California, called the ongoing feud between Trump and Haley “exciting.” Haley has likely taken a cue from Trump, the master at smash-mouth politics, Steel said.

“He's a Ph.D. — he's taught many other people how to do it,” said Steel. “So she's picked up the lesson.”

It took Haley a while to get here.

The former South Carolina governor initially said she wouldn’t run if Trump decided to seek another term. When she did anyways, she kept her critiques of her former boss to a minimum, sticking to a more straight-laced, traditional style of campaigning.

She paired remarks about Trump being “the right president at the right time” with criticism like “chaos follows him” as she tried to siphon away some of the former president’s soft supporters while also appealing to Republicans and independents who opposed him.

By the time Haley hit New Hampshire, the field was shrinking and she was ramping up her criticisms. She accused him of costing the party three straight federal elections and of throwing “temper tantrums” as she criss-crossed the state with GOP Gov. Chris Sununu, a vocal Trump critic, by her side.

But she didn’t truly unload on Trump until she’d already lost to him by 11 points in the state. “Bring it, Donald,” she declared in her concession speech. She told CNBC she only waited to hammer Trump because when the field of candidates was larger, she had “others I had to get out of the way.”

“Nikki Haley has to do something to shake up the race,” said Mike Dennehy, a New Hampshire-based GOP strategist who worked on John McCain’s presidential bids. “In her view, she thinks she has a chance and this is the only way.”

Haley, unsurprisingly, has provoked the ire of the former president and frontrunner for the nomination, who has — at times — pushed racist and conspiratorial attacks back at her.

“Anybody that makes a ‘Contribution’ to Birdbrain, from this moment forth, will be permanently barred from the MAGA camp,” Trump posted on Truth Social. “We don’t want them, and will not accept them, because we Put America First, and ALWAYS WILL!”

The threat turned into a badge of honor for Haley. Her campaign sold out of printed t-shirts that read, “Barred. Permanently,” and fundraised off Trump’s post, raking in more than $2.5 million in the 48 hours following her speech in New Hampshire.

But Trump has kept at it. On Thursday, in an effort to belittle the former South Carolina governor in her home state, his campaign held a press conference with elected officials from the state focused squarely on her record.

Trump’s allies, meanwhile, warn that Haley’s continued attacks against her former boss could hurt her down the road.

“She's pushing herself into the Liz Cheney or Adam Kinzinger category, and that’s not a great spot for someone who wants a future in the Republican Party,” said Alex Bruesewitz, a Trump ally and GOP consultant. “I bet Trump is looking forward to defeating Nikki in her home state. He’ll never let Nikki live that down.”

Still, Haley’s second-place finish in New Hampshire suggests that — even if not a majority — she has a sizable constituency. And Trump’s threats have not cut Haley off from wealthy Republican donors. On Wednesday, she attended a fundraiser on Trump’s home turf in Palm Beach, Florida that included billionaire Ken Langone and financier and former Romney finance chair Spencer Zwick.

Steel shrugged off the idea that Haley is jeopardizing her political future by laying so hard into Trump, pointing to the knock-down, drag out fight in the final days of the 2016 Republican primary.

“I don't think anybody was sassier on Trump than Ted Cruz. That was a great, spectacular mud fight,” Steel said. “And they get along well now.”

For Haley, the first, small test of the effectiveness of her more pugilistic approach will come this week. While she has ceded the Nevada caucuses to Trump — appearing instead on the state-run primary ballot, which will not award delegates to the national convention — Haley is competing in a little-noticed nominating contest in the Virgin Islands, campaigning virtually and sending surrogates there.

“We’ll find out in the Virgin Islands caucus ... whether her newfound strategy of attacking President Trump is effective or not,” said John Yob, a Republican presidential campaign veteran, who is running for RNC committee member in the islands.