How do you challenge Trump for the nomination? With Nikki Haley in, let's count the ways.

He reshaped the Republican Party in his image and won the party's last presidential nomination by acclamation.

So how do GOP hopefuls challenge Donald Trump for 2024?

Nikki Haley, the former U.N. ambassador and South Carolina governor, on Tuesday announced her campaign with release of a video; her opening rally is set for Wednesday. She became the first official alternative to the former president, though she almost certainly won't be the last. Governors, senators and other veterans of the Trump administration are testing the waters and traveling to states that host the crucial early contests.

Trump announced his own campaign just a week after the midterm elections in November, although there had been little doubt he would seek to become just the second commander-in-chief to serve nonconsecutive terms.

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He is still the sun in the Republican solar system, his challengers moons in his orbit – defined most of all by their relationship with or against him.

For those now calculating their campaigns, the trouble with Trump is not only the task of defeating him for the nomination. It's doing so in a way that doesn't repel the hefty fraction of Republican voters who remain fiercely behind him. If the former president is vanquished for the nomination, and angry about it, there's a risk he could sabotage the general-election prospects of whomever wins it.

Among Democrats, by contrast, President Joe Biden seems to be in a situation akin to the one Trump faced as the incumbent in 2020. Though there are some quiet concerns, including his age, Biden doesn't yet face a credible challenger for the nomination, which gives him the luxury of delaying his own announcement as the other side begins to fight things out.

The White House race: Nikki Haley goes on offensive in first 2024 campaign rally

"Haley’s entrance officially kicks off a messy 2024 primary race for the MAGA base that has long been brewing," Democratic national chair Jaime Harrison said, a reference to Trump's signature "Make America Great Again" slogan. "Everyone get your popcorn.”

Here are four different strategies in the works:

The next-generation Trump

In her 3½-minute video, Nikki Haley doesn't mention Trump's name or show his face. She includes footage that depicts her on the job at the United Nations – courtesy of the former president – but focuses more on her two terms as governor of South Carolina, a post she won on her own.

More: Nikki Haley announces 2024 presidential bid in first major GOP challenge to Donald Trump

She does note Republicans have lost the popular vote in seven of the past eight presidential elections. (Unsaid: That includes Trump's two races.) "That has to change," she declared, saying it was time for a "new generation" of leaders and flashing the words "NEW GENERATION" on the screen to make sure no one missed the point. Haley is 51; Trump is 76.

Another potential contender from South Carolina, Sen. Tim Scott, also makes a generational argument. He is 57.

But Haley doesn't make a significant break with Trump on immigration or other policies, and she echoes his culture war attacks, saying the "socialist left" wants to distort American history.

Trump's spokesman responded to the announcement by blasting Haley as "a career politician whose only fulfilled commitment is to herself." Two years ago, she said she wouldn't seek the nomination if Trump decided he wanted it again.

Who's Trump?

Florida Gov. Ron DeSantis has emerged as the strongest early challenger to Trump, his onetime political benefactor. In a USA TODAY/Suffolk University poll in December, two thirds of Republicans and those inclined to vote Republican preferred DeSantis over Trump for president by double digits, 56%-33%.

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That has gotten Trump's attention. He has dubbed him "Ron DeSanctimonious" and denounced him as a "RINO GLOBALIST" – that is, a "Republican In Name Only" on issues of foreign policy. On his social media account on Truth Social this month, Trump shared a photo of a man, purportedly DeSantis, with three young women and the caption "Here is Ron DeSanctimonious grooming high school girls with alcohol as a teacher."

Trump commented on it, "That's not Ron, is it? He would never do such a thing!"

The two men had once been allies. In 2017, Trump endorsed him for governor before DeSantis, then a member of Congress, had formally announced his candidacy. Trump now accuses him of disloyalty.

DeSantis doesn't seem to be listening. He ignores Trump's attacks and tries to avoid even using his name.

"I spend my time delivering results for the people of Florida and fighting against Joe Biden – that's how I spend my time," DeSantis said at a news conference when asked about the latest volleys from Mar-a-Lago. "I don't spend my time trying to smear other Republicans."

Whoever those unnamed "other Republicans" might be.

The Trump-without-the-baggage

After four years of unblinking loyalty as Trump's vice president, Mike Pence doesn't have the option of not acknowledging his former boss' existence, or of his ties to him.

Instead, Pence has been embracing Trump's record on the economy, immigration, the pandemic and foreign policy, arguing he deserves a share of credit for the administration's achievements. But Pence also points out their greatest breach: when he refused Trump's entreaties to try to overturn the results of the 2020 election on Jan. 6, 2021.

"Everywhere I've gone across the country, I hear people that are very proud of the record of the Trump-Pence administration," Pence told USA TODAY in November. "But almost in the same breath, I hear people say they want leadership that reflects the respect and civility that most Americans practice every day."

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In the most recent USA TODAY/Suffolk poll, Republicans and Republican-leaning voters by 2-1 said they wanted Trump's policies but a different standard-bearer to carry them.

Call it Trumpism without Trump. Trump policies without the debunked allegations of 2020 election fraud, the legal troubles, the inflammatory tweets, the derisive nicknames.

That's also akin to the pitch another veteran of the Trump administration, former Secretary of State Mike Pompeo, is making as he considers a presidential bid.

The Anti-Trump

New Hampshire Gov. Chris Sununu offers a clean break with Trump and the political era he has dominated.

The former president's appeal has waned, Sununu said this month on ABC's "This Week." "Unfortunately, at the end of the day, November of '22 showed us that, right? Trump is going to be seen as a very extreme candidate. The country is going to push back against it."

He predicted, "He could get the nomination, but he can't get it done" to win the general election.

Sununu, who in November won his fourth term as governor, said his prospective presidential bid would offer "new leadership" and a "New Hampshire model" of limited government and conservative fiscal policies. The more traditional Republican agenda stands in contrast to Trump's populist message.

The Granite State governor also dared to take a sharper shot at Trump than any of his prospective 2024 rivals when he addressed the Gridiron Dinner in Washington last year.

"The press often will ask me if I think Donald Trump is crazy, and I’ll say it this way: I don’t think he’s so crazy that you could put him in a mental institution," he joked. "But I think if he were in one, he ain’t getting out."

Former Maryland Gov. Larry Hogan, who is considering a 2024 bid, also openly broken with Trump.

But it is a sign of Trump's continued dominance of the GOP that the contenders in this category are seen as the longest shots to claim the nomination.

This article originally appeared on USA TODAY: How Nikki Haley and other Republicans are challenging Trump for 2024