COLUMBIA, S.C. — The number of candidates on stage is shrinking, but the fundamentals of the Republican presidential debate on Wednesday may be familiar to anyone who has watched the previous three meetings.

No one has yet emerged as the clear Republican alternative to former President Donald Trump, whose has skipped all the debates. Former United Nations Ambassador Nikki Haley and Florida Gov. Ron DeSantis appear to be leading the fight for second, yet conservative entrepreneur Vivek Ramaswamy and former New Jersey Gov. Chris Christie are still factors.

What time is the Republican debate?

The two-hour debate will start at 8 p.m. Wednesday. It’s being moderated by NewsNation's Elizabeth Vargas; Megyn Kelly, host of “The Megyn Kelly Show” on SiriusXM; and Eliana Johnson, editor-in-chief of the Washington Free Beacon.

What channel is the Republican debate on?

NewsNation says the event will air on its website and streaming platforms. It will be broadcast live on the CW network in the eastern half of the country and tape-delayed out West. NewsNation has been soliciting audience questions via an online submission form.

The Republican National Committee has partnered with Rumble — a video-sharing platform popular with some conservatives — to livestream the debate.

Where is the Republican debate?

The setting for the fourth GOP debate is the Moody Music Hall at the University of Alabama in Tuscaloosa.

Alabama voters will make their presidential picks on March 5, part of more than a dozen Super Tuesday states. That's when the largest number of delegates is up for grabs of any single day in the primary cycle.

In general elections, the state has been in the red column for decades, last supporting a Democrat for president when Jimmy Carter ran in 1976.

Which candidates will be on stage?

Four Republicans will be on the debate stage, as polling and donor benchmarks for qualification rise.

DeSantis, Ramaswamy, Haley and Christie met the Republican National Committee's requirements to participate in Wednesday's event.

South Carolina Sen. Tim Scott was on stage for the third debate but has since shuttered his presidential campaign. North Dakota Gov. Doug Burgum, who didn't qualify for the third debate, suspended his campaign earlier this week.

Trump will hold a fundraiser in Florida in lieu of participating.

Small stage, big opportunity

Fewer candidates, of course, means more airtime for each on national television. The big question: Can any of the participants take advantage of the opportunity and change the trajectory of the race?

This is the final scheduled debate, although at least one more is likely in the days before Iowa’s Jan. 15 caucuses.

Can Haley convince skeptical Republicans?

Of all the candidates on stage, Haley has shown real signs of interest growing in her campaign, including high-profile endorsements, large crowds and some polling gains in key early states.

But she’s most popular among the donor class, moderates and the NeverTrump wing of the party. To take a big step forward, she needs to convince more hardcore conservatives and Trump voters that she’s conservative enough.

In recent days, DeSantis has gone after Haley for supposedly embracing a liberal policy on legal immigration and for failing to wade into the fight over transgender bathroom use while she was South Carolina's governor.

Eight Republicans stood on the debate stage in August. Four months later, four remain. Trump's Republican critics believe he can be beaten only if the field shrinks to the point where a single alternative emerges in the coming weeks or months.

Already, pressure is building on Christie and Ramaswamy to get out of the race. Even DeSantis is on shaky ground given his stagnant polling numbers and a weekend staffing shake-up at his super PAC.