TUSCALOOSA, ALA. — The fourth Republican debate on Wednesday in Alabama is both starkly different and strikingly similar to the previous three GOP showdowns.

The 8 p.m. NewsNation debate will feature the smallest stage yet, with just four candidates as the field tightens. It’s also the first in the heart of the Deep South after previous events in swing-state Milwaukee, blue Los Angeles and bustling Miami.

Like its predecessors, it will feature Republican rivals fighting to assert themselves as Donald Trump’s foremost rival. And like its predecessors, it will go on without the former president, who plans to boycott the event, confident in national and state polls that show him with a commanding lead.

The previous debates have had only limited impact on the GOP race, as each Republican strove for an elusive breakout moment amid declining audiences and waning interest.

Even so, the debate Wednesday at the University of Alabama’s Moody Music Hall could offer voters a clearer view of Trump’s top Republican alternatives thanks to the strictest candidate qualification requirements yet and a smaller group of candidates.

Former New Jersey Gov. Chris Christie, Florida Gov. Ron DeSantis, former U.N. Ambassador Nikki Haley and biotech entrepreneur Vivek Ramaswamy will share the stage in what could be the last debate sponsored by the Republican National Committee.

Here’s what to watch:

A SMALLER FIELD. The long-awaited winnowing of the Republican race has begun after U.S. Sen. Tim Scott of South Carolina and former Vice President Mike Pence suspended their campaigns. This week, North Dakota Gov. Doug Burgum tapped out, too.

That means there’s more airtime for the four other contenders to promote their policies, highlight their differences with Trump and clash among themselves.

But Trump’s boycott has also lessened the stakes and alienated viewers. The audience has sunk from nearly 13 million viewers in the Fox News clash in Milwaukee in August — on the eve of Trump’s surrender to Georgia authorities — to about 7.5 million for last month’s Miami event.

Since that debate, Scott and Burgum have both ended their campaigns, shifting attention to the quartet of remaining top contenders. But with the holiday season approaching — and the Iowa caucuses looming in January — the window is closing to win over distracted voters.

ATTENTION! As the first rounds of voting near, candidates are going to lengths to attract eyeballs — including the unconventional debate last week in metro Atlanta between DeSantis and Gov. Gavin Newsom of California, a Democrat who isn’t in the presidential race.

That’s why Wednesday’s debate could deliver the biggest moments yet in a campaign so far shaped by Trump and the criminal indictments he faces in Atlanta and three other jurisdictions.

Wednesday's debate will be the second in as many weeks for Florida Republican Gov. Ron DeSantis, left on the screen, who faced off last week in Alpharetta against California Gov. Gavin Newsom, a Democrat who isn't running for president. (Justin Sullivan/Getty Images/TNS)

Credit: TNS

icon to expand image

Credit: TNS

DeSantis has been particularly eager to demonstrate he’s still the dominant Trump alternative after ceding ground to Haley in recent polls. With his super PAC in flux and his campaign shifting staff to Iowa, he’ll be under pressure from donors and supporters for a memorable showing.

Haley, meanwhile, has benefited from new attention on foreign policy after the Oct. 7 Hamas attack on Israel that has erupted into a wider conflict.

She recently compared DeSantis’ campaign to a “dumpster fire,” but she’s reserved her harshest words for Ramaswamy. In the last showdown, Haley called the first-time candidate “scum” after he criticized her adult daughter for using the TikTok social media site.

CHRISTIE’S MOMENT? Facing growing pressure to drop out of the race, the New Jersey Republican has staked his entire campaign on the New Hampshire primary. He’s betting that his outspoken criticism of Trump will set him apart from his more circumspect opponents.

Christie has shown no signs of shifting his approach — and Wednesday’s debate could give him a nationally watched platform to again pummel Trump while also pressing other Republicans to take the same tactic.

“If you want to beat someone,” he said on Fox News this week, “you need to go out and tell people why he’s not right for the job — and why you are.”

TRUMP’S NO-SHOW. The former president’s decision to skip the debates has so far paid dividends by turning what was expected to be must-watch TV into a sideshow that, in some cases, is largely forgotten by the next morning.

But he’s mixing up his strategy for Wednesday’s showdown. Instead of staging a major rally or a competing interview, Trump is hosting a private fundraiser in Florida that will capture limited media attention while his rivals take the stage.

There’s little sign, though, Trump will shift to the defensive even as he savages his rivals. He told supporters this week that he delights in watching DeSantis plummet “like a very seriously wounded bird.” And he’s called Haley, a key member of his administration, a “birdbrain.”

Trump, of course, has his own challenges, starting with criminal indictments that have threatened to upend his hopes to return to the White House. And while polls have shown President Joe Biden slipping in battleground states, the dynamics of a potential rematch remain tight.

HOW TO WATCH. The two-hour debate will start at 8 p.m. and air on NewsNation and the CW network, both owned by the Nexstar Media Group. It will be moderated by podcast star Megyn Kelly, a former Fox News host; Eliana Johnson of the conservative Washington Free Beacon; and Elizabeth Vargas, a former ABC News anchor who hosts a NewsNation show.