I’ll be watching Ramaswamy tonight, who will be center stage next to DeSantis, a position I did not foresee for the biotech entrepreneur when he first jumped into the race in February. But Ramswamy is on an upswing, soaring from a virtual unknown to garnering nearly 10 percent in FiveThirtyEight’s national polling average. Without Trump on the stage and with DeSantis’s polling average trending downward, is it Ramaswamy’s moment to own it?

Ramaswamy has staked his candidacy on an anti-woke, pro-capitalist message, promising to guide the country at a revolutionary moment by recognizing 10 simple truths. He’s a 38-year-old millennial leaning into the culture wars from the right who often seems to say exactly what pops into his head. This style has so far made him a major candidate. We’ll see tonight whether it appeals to voters. Thirty percent of likely Republican primary voters view him favorably, according to a FiveThirtyEight/Washington Post/Ipsos poll released today, and only 10 percent view him unfavorably. That leaves a huge chunk of voters in the middle who say they don’t know much about him and who may be seeing him speak at length for the first time during the debate. How he performs — whether it involves quoting Eminem or not — could leave a lasting impression. And a newcomer without political experience coming out of nowhere to win the Republican nomination? It’s something we’ve seen before.

–Analysis from Monica Potts

I’m tracking Burgum and Haley tonight. In another universe, the two might be top-tier contenders — a billionaire two-term governor from the heartland with great hair, and a trailblazing former governor and U.N. Ambassador long seen as a rising star in the GOP — but neither have made much of an impact on the race so far. Haley had a brief moment of prominence in February, when she was the first non-Trump candidate to jump in the race, but has since polled consistently in the low single digits. Haley will be the only woman on stage, and she may try to play to her strengths by drawing sharp foreign policy contrasts with higher-polling contenders like DeSantis and Ramaswamy (who she went after over Israel policy this week). Most of the attention Burgum has received surrounds his innovative tactic of paying people to donate to his campaign. The North Dakotan has been polling marginally better in Iowa and New Hampshire, where he’s spent millions on TV ads. If he makes it to this debate — he was in the emergency room earlier due to a basketball-related injury — his task will be to tell voters who he is, since he’s one of the least-known people on the stage, and maybe sell his Trump-free economic argument.

–Analysis from Jacob Rubashkin, Inside Elections

Tonight I’m on Pence and Hutchinson duty. Neither candidate appears to have a great shot at winning the primary — the former vice president is at 4 percent in FiveThirtyEight’s national polling average while the former Arkansas governor hasn’t even garnered 1 percent — but Pence at least has a decent chance of making a debate-night splash. Given the events of Jan. 6, 2021, Pence has the strongest claim to the anti-Trump “lane” of the primary. I wouldn’t be surprised if we saw some real fireworks between him and the GOP candidates who have been quick to jump to Trump’s defense after the bad news he has been hit with over the past year. For his part, Hutchinson will have to pull off a masterclass in persuasion and performance to gain substantial ground. In our poll with Ipsos and The Washington Post, only 6 percent of Republicans said they were even considering voting for him, much less were intending to do so. In a more fluid primary, he’d maybe have a shot at doing something about that. But with Trump as the default and other candidates leading the various anti-Trump lanes, those are really tough numbers to come back from.

–Analysis from G. Elliott Morris_

I’m watching DeSantis tonight. The Florida governor really needs a good performance tonight to reestablish himself as the main alternative to Trump after seeing his national polling average slip from 36 percent in mid-March to just 15 percent today. It will be interesting to see how much he goes after the absent Trump — which has typically been his strategy to this point — versus attacking the other not-Trumps, who are realistically his main competition these days. I’m also curious what bar DeSantis will be measured against. The popular narrative about him is that he’s kind of awkward, so maybe a quote-unquote “presidential” performance will be reassuring to people who are on the fence about him. But our poll with Ipsos and The Washington Post actually found that voters have relatively high expectations when it comes to DeSantis’s debating abilities, so maybe he needs a truly masterful performance in order to move the needle.

–Analysis from Nathaniel Rakich

Haley, as a former ambassador, made an impassioned case for the U.S. continuing military and financial aid to Ukraine amid Russia's invasion.

"When you look at the situation, you have a pro-American country that was invaded by a thug," she said. "You want to talk about what has been given to Ukraine, less than 3.5% of our defense budget has been given to Ukraine. If you look at the percentage per GDP, 11 of the European countries have given more than the U.S."

She was interrupted by Ramaswamy, who is opposed to further assistance, and the two had a fiery back-and-forth.

Haley told the political newcomer: "You have no foreign policy experience and it shows."

On Ramaswamy's approach to Putin, Haley said: "This guy is a murderer and you are choosing a murderer."

-ABC News' Alexandra Hutzler