Wednesday night's Republican presidential debate, hosted by CNBC, is the first encounter during which Donald Trump is seeing his front-runner status seriously challenged, as Ben Carson is now on top in four polls of Iowa Republican primary voters, as well as in a national survey published on Tuesday by CBS News and The New York Times.

Consequently, the focus of the event will most likely be squarely on the real-estate tycoon and the former neurosurgeon, for both of whom the debate could well mark a make-or-break moment, The Hill reported.

Carson, now widely viewed as the new GOP front-runner, may need to adapt his "calm demeanor," which tends to come across as "low energy" on television.

"He needs to be polished, clear and strong tonight," Republican consultant Matt Mackowiak said. "Ben has said he's going to stay who he is and he wouldn't want to get elected being somebody else," said Ryan Rhodes, Carson's Iowa state director, according to CNN.

"He does not need to tear someone else down to build himself up."

Trump, for his part, has to once again prove his credibility and will be tempted to go hard after Carson, now his main challenger. But hitting his rival in his trademark personal manner may prove risky for the former "Apprentice" star since the surgeon has the highest net favorable rating among GOP White House hopefuls, Mackowiak said.

For the remaining candidates in the still crowded Republican field, meanwhile, they have some catching up to do. That is especially true for former Florida Gov. Jeb Bush, who has had long been seen as serious challengers but have struggled to gain traction in polls.

"[Bush] needs to have a performance that stands out from the crowd. He won't be center stage this time so he need to, in words and actions, figure out how not to fade into the wings," said Katie Packer, deputy campaign manager for Mitt Romney's 2012 campaign.

Also trying to make inroads with GOP voters on Wednesday will be New Jersey Gov. Chris Christie, Texas Sen. Sen. Ted Cruz, former Hewlett-Packard CEO Carly Fiorina, former Arkansas Gov. Mike Huckabee, Ohio Gov. John Kasich, Kentucky Sen. Rand Paul and Florida Sen. Marco Rubio.