- Donald Trump has won the last 3 states in a row. Will he go for the kill?
- Can Marco Rubio and Ted Cruz stop fighting each other long enough to hit Trump?
Here are five things to watch at Thursday's debate:
Time for Donald Trump to go in for the kill?
Donald Trump is on a roll, and it's not clear what, if anything, can stop him.
"It's going to be an amazing two months," Trump said in his Nevada victory speech Tuesday night. "We might not even need the two months, folks, to be honest."
If the past six months offer any indication, Trump's performance at Thursday's CNN debate is unlikely to sway the Republican electorate either for or against him. The New York businessman has had shaky debates and has frequently been the favorite target on stage, but he's never lost serious momentum in the polls after a bad evening.
Still, the prime-time event will be telling -- will he give Cruz and Rubio any breathing room to make their case? And how will he respond when attacked?
Trump has angrily gone after Cruz over the last few weeks, calling the Texas senator a "liar" and raising ethical questions about his rival's campaign tactics. But he has largely steered clear of targeting Rubio with the same level of intensity. If Rubio tries to pick a fight with Trump, that would likely change quickly.
And for anyone wondering if this will be the debate where a more presidential Trump takes the stage, don't hold your breath. Although he has repeatedly promised that he would use a different tone if elected to the White House, he hasn't seemed interested in doing so as a candidate.
Just this week, Trump stirred up fresh controversy by saying about a protester at a campaign rally: "I'd like to punch him in the face."
Can Ted Cruz bounce back?
It's been a rough week for Ted Cruz.
He finished behind Trump and Rubio in both South Carolina and Nevada, a letdown after his cycle-opening victory in the Iowa caucuses.
And the conservative senator, whose campaign slogan is "Trusted," has been dogged by relentless accusations from his rivals of running a dishonest campaign and of deploying dirty political tactics.
The ethics questions started in earnest in Iowa. On the night of the GOP caucuses there, the Cruz campaign falsely told voters that Carson was dropping out of the race. Since then, Cruz's rivals have slammed the senator of lying to get ahead, with Trump being particularly aggressive in his stump speeches and on social media. And Monday, Cruz fired his communications director, Rick Tyler, after he circulated a video that falsely depicted Rubio saying there were "not many answers" in the Bible, when in fact, Rubio had said "all the answers are in there."
Thursday night, expect to see a feistier Cruz.
A Cruz adviser said this week that the senator has reached a boiling point with Trump, and that Cruz is prepared to be noticeably more aggressive as he defends himself from the stream of character attacks.
Time is of the essence for Cruz. His campaign has always emphasized the importance of the March 1 contests, one of which will take place in Cruz's home state of Texas.
"One week from today will be the most important night of the campaign," Cruz said Tuesday.
Can Marco Rubio rise to the occasion?
The South Carolina GOP primary was hugely critical for Marco Rubio. He came in at second place, narrowly beating Cruz, but more importantly, forced Jeb Bush out of the 2016 race.
"This has become a three-person race, and we will win the nomination," Rubio told his supporters on election night.
What Rubio meant was this: he was claiming the establishment mantle and would position himself the candidate to take on Trump and Cruz.
But just because there's an opening for establishment support doesn't mean Rubio will automatically get it. He needs to show Thursday night he can step up.
The Florida senator has been dogged by questions about his readiness for the presidency. One of the low points of his campaign came at a debate in New Hampshire this month, when New Jersey Gov. Chris Christie unleashed a blistering attack on Rubio, accusing the first-term senator of lacking substance.
One thing Rubio hasn't seemed too keen on is to go on the attack against Trump, even as the GOP front-runner racks up more and more delegates.
But on the eve of the debate, Rubio took the rare step of calling out Trump by name on the stump, offering a possible preview of what's to come on the debate stage.
"The front-runner in this race, Donald Trump, has actually alluded to the fact that parts of Obamacare are pretty good," Rubio said in Houston. The senator also went after his rival on the Middle East, telling voters that Trump doesn't want to "take sides on Israel versus the Palestinians because he wants to be an honest broker."
"There is no such thing as an honest broker in that," Rubio said.
John Kasich under fire to get out
Republican Party leaders and major donors are starting to get annoyed at John Kasich.
The Ohio governor had an impressive second-place finish in New Hampshire earlier this month. But now, with establishment Republicans increasingly anxious about the possibility of Trump or Cruz winning the nomination, there is growing concern that Kasich is crowding the establishment lane -- that is, pulling away votes from Marco Rubio.
On the debate stage Thursday night, Kasich will be under more pressure than ever to prove why he's still here.
So far, Kasich has shown no signs of abandoning his campaign. Running on a more moderate -- and positive -- message, the governor is eying possible victories in Southern and Midwestern states, including Ohio.
He's also dismissed the suggestion that some donors were eager to see him ditch his campaign.
"I haven't heard from any of the special interests to get me to drop out," Kasich told CNN's Wolf Blitzer this week. "We're signing up some significant Republican fundraisers and our political organization is expanding as well."
Ben Carson, odd man out
Yes, Ben Carson is still running for president.
The retired neurosurgeon had a brief moment at the top of the polls, but that was already several months ago. Since then, he's come in at fourth place in the Iowa caucuses, eighth place in the New Hampshire primary and last place in the South Carolina contest on Saturday.
Over the course of several weeks, a slew of Carson's rivals have abandoned their White House bids. But Carson is still hanging on -- even as he himself appears fully aware that he has been sidelined in the race.
"Thank you for including me in the debate," Carson joked at the last GOP debate in South Carolina. "Two questions already -- this is great."