Expect Trump and Cruz to be in the center ring. The others will be scrambling to keep up. Here's a summary from The Hill.
Nine contenders will take the stage for the main clash on CNN, but the most intense focus will fall on two candidates: businessman Donald Trump, who has led the national polls for several months, and Sen. Ted Cruz (Texas), who is rising fast and has snatched the lead from Trump in Iowa.
Third-placed Sen. Marco Rubio (Fla.) will also be hoping to consolidate his position as a candidate able to straddle the GOP’s conservative-establishment divide.
Meanwhile, middle-ranking contenders will be looking for a breakout moment to vault into the top-tier, while the candidates struggling for traction will seek to avoid the fate of former Arkansas Gov. Mike Huckabee who, for the first time, is relegated to the earlier “undercard” debate.
Here's the look at the top two.
Businessman Donald Trump
Trump is polling at almost double the level of the second-placed Cruz in national surveys. That means the real-estate magnate will be center stage — exactly where he likes to be — on Tuesday night.
Trump can expect to face tough questioning on his recent call to bar Muslims from entering the United States, but several recent polls have indicated that a large swath of the GOP electorate agrees with him.
A much trickier question for Trump is how to handle Cruz. The real estate mogul has blasted the senator in recent days, telling “Fox News Sunday” that Cruz behaves in the Senate “like a bit of a maniac” and asserting on CNN’s “State of the Union” that he has “far better judgment than Ted.”
If Trump backs away from those attacks in the debate, he risks looking uncharacteristically weak. But if he goes after the Texan, a skilled debater, there is the possibility of him getting caught with the kind of verbal uppercut he has avoided in the four debates so far.
Sen. Ted Cruz (Texas)
Can Cruz keep his momentum going? He has enjoyed strong showings in the debates to date, but other candidates are much more likely to train their fire on him now that he has risen in the polls.
Rubio, for instance, suggested during an appearance on NBC’s “Meet the Press” on Sunday that Cruz’s tough talk on national security was misleading and accused him of adopting an “isolationist” approach.
Cruz will want to come out of Tuesday night’s clash with his conservative credentials intact, even as he seeks to parry whatever attacks Trump throws his way.
One more strong debate performance could put Cruz in pole position for the nomination.
Check The Hill's report for observations and speculations about the other seven.