The talk stage in Tuscaloosa, Ala., can be down to 4 Republican presidential hopefuls on Wednesday — with the front-runner, Donald J. Trump, nonetheless absent — as the crucial to break from the dwindling pack grows extra intense lower than six weeks earlier than the Iowa caucuses.

Gov. Ron DeSantis of Florida and Nikki Haley, the former governor of South Carolina, are in a slugfest to declare the mantle of Mr. Trump’s important different, and all that will include that: marketing campaign donations, late endorsements and the doable votes of independents and even Democrats alarmed by Mr. Trump’s authoritarian language and plans to enact a extra radical agenda.

However the two different candidates onstage, the entrepreneur Vivek Ramaswamy and former Gov. Chris Christie of New Jersey, will do all they will to seize the highlight in the hope of revitalizing their flagging campaigns.

The “will he or won’t he” hypothesis about whether or not Mr. Trump would take part in the earlier debates in Wisconsin, California and Florida is gone forward of the gathering in Alabama. The previous president’s determination to sit out the occasions has not harm his standing in the polls, and the query for many now could be whether or not he would present up to a debate in the basic election subsequent fall.

However as the discipline narrows by attrition, the last 4 can have extra time to make an impression on Republican major voters who’ve but to resolve.

Gov. Doug Burgum of North Dakota on Monday turned the newest candidate to drop from the race, though he had failed to make the stage for the final debate. The withdrawal of Senator Tim Scott of South Carolina can be felt extra acutely, since he in all probability would have certified for Wednesday’s occasion. His debate performances have been largely unremarkable however he made a small splash in Miami final month when he confirmed up along with his girlfriend.

Essentially the most memorable strains of the final two debates concerned Ms. Haley skewering Mr. Ramaswamy. In September, she instructed her youthful rival, “Every time I hear you, I feel a little bit dumber,” and final month she referred to as him “just scum.”

These strains elevate an necessary query for Mr. DeSantis as he tries to fend off Ms. Haley’s rise in the polls: Can he take her on extra straight and win?

Mr. Ramaswamy seems possible to proceed his technique of denigrating and baiting all of his opponents besides for Mr. Trump, although the efficacy of his insult-driven blitzkrieg appears to have diminished since he shocked the discipline in Milwaukee in August. In Iowa Metropolis on Saturday, he mentioned he had been “brutally frank in the last debate,” including, “I don’t intend to stop doing that now.”

Mr. Christie faces a loftier query: Is his acknowledged objective of thwarting one other Trump presidency higher served by dropping out and letting a rival consolidate the anti-Trump vote?

The previous South Carolina governor has parlayed her debate performances into an actual sense of momentum. Sure, she stays far behind Mr. Trump, the man who made her his first United Nations ambassador, in nationwide polling, however her trajectory is on a gradual, regular climb, in contrast to these of her onstage rivals.

Wednesday’s debate is the first since the political community based by the billionaire conservatives Charles and David Koch endorsed Ms. Haley, promising to mobilize a military of grass-roots door tits behind her. Additionally it is the first since Jamie Dimon, the chief government of JPMorgan Chase, started encouraging different main donors and Democrats to again her as the final hope of thwarting Mr. Trump’s nomination.

She wants to reassure these new backers that they made a stable wager. To try this, she can have to discover the zingers she used to dismantle Mr. Ramaswamy, and flip them on the candidate now in her sights, Mr. DeSantis.

She nonetheless wants to determine, nonetheless, whether or not she is the candidate for these inside her celebration and out who concern and detest Mr. Trump, or whether or not she needs to attraction to Trump supporters as a contemporary face to choose up his mantle. If she is the former, she might solely get up to now in a G.O.P. that also broadly approves of the former president. Interesting to Trump likers and loathers has been the trick that no Republican has solved.

After taking glancing photographs at Mr. Trump for months, Mr. DeSantis laid into him at size on Tuesday.

He castigated Mr. Trump for bragging about the endorsement of a Black Lives Matter activist, for criticizing Mr. DeSantis’s strongly anti-abortion report, and for in some way blaming the Florida governor for the Faculty Soccer Playoff choice committee’s snub of Florida State College, which was not chosen to vie for the championship regardless of an undefeated season. (The College of Alabama, in Tuscaloosa, was the beneficiary of that snub, so watch for school soccer speak on Wednesday evening.)

However Mr. DeSantis’s important criticism was of Mr. Trump’s refusal to debate: “I don’t think he can stand there for two hours against me and come out on top,” he mentioned. “I think they know that, and I think that’s why they’re not doing it.”

Clashing with Mr. Trump is significant; in spite of everything, you may’t win the nomination with out beating the front-runner. However Mr. DeSantis has to blunt Ms. Haley’s rise as properly.

In Tuscaloosa, Mr. DeSantis wants to take the microphone away from Mr. Ramaswamy, who has faded to fourth place in nationwide polling averages. Ms. Haley, in contrast, is now solidly in second place in New Hampshire, neck and neck with Mr. DeSantis in Iowa and threatening him nationally.

Mr. DeSantis’s urgent job is to reassert his standing as the Trump different, and for him to try this, the debate can not devolve once more right into a cage match between Ms. Haley and Mr. Ramaswamy.

For causes of ego, unrelenting self-confidence or designs on his future, Mr. Ramaswamy, a political neophyte with nary an elected workplace to his identify, might be not leaving the major race anytime quickly. The cash he’s spending from his personal financial institution accounts — $17 million as of Sept. 30 — can preserve his marketing campaign afloat so long as he needs.

Mr. Christie is, in many respects, Mr. Ramaswamy’s reverse, a profession public servant with out a huge fortune to faucet, whose marketing campaign’s raison d’être is to diminish Mr. Trump’s stature, not to lionize him as the twenty first century’s biggest president. However the former New Jersey governor finds himself at a crossroads in Tuscaloosa.

He barely made the debate stage, simply qualifying below the Republican Nationwide Committee’s tightening necessities — polling at 6 p.c or increased in nationwide or early-state polling, and garnering 80,000 distinctive donors.

And his third-place standing in New Hampshire, with round 12 p.c of the vote, could possibly be seen both as a energy or as a spoiler for the aspirations of the candidate in second place, Ms. Haley, who wants a powerful displaying in the Granite State to slingshot her into the major contest in her dwelling state, South Carolina.

Mr. Christie continues to denounce Mr. Trump’s health for workplace in methods his Republican rivals received’t, difficult the former president as a would-be dictator threatening to finish democracy as we all know it. However that line of assault has proved ineffective amongst Republican major voters.

The 2016 presidential marketing campaign may look like historical historical past, however for many Individuals, Mr. Trump’s remedy of Megyn Kelly, then a Fox Information anchor, throughout the debates secured his popularity as a misogynist.

After Ms. Kelly questioned him forcefully in one debate, he got here again with, “You could see there was blood coming out of her eyes, blood coming out of her wherever.” Ms. Kelly was defiant in the face of offended Trump supporters, declaring that she would “not apologize for doing good journalism.”

Wednesday’s debate, which can be carried by a cable information newcomer, NewsNation, can have a significantly smaller viewers than these Fox showdowns in 2015 and no Mr. Trump — however Ms. Kelly, who now hosts “The Megyn Kelly Show” on Sirius XM, can be again.

Little doubt, she can be powerful on the 4 individuals. The query is, how onerous will she press them to tackle Mr. Trump?

Ms. Kelly can be sharing the moderators’ desk with Elizabeth Vargas of NewsNation and Eliana Johnson of the Washington Free Beacon, an all-female panel tilted to the proper. The talk can be televised on the CW beginning at 8 p.m. Jap time, and streamed on the NewsNation web site and the conservative social media web site Rumble.

Anjali Huynh and Maggie Astor contributed reporting.