10 Candidates, 10 Things They Need to Prove at the First Republican Debate

— -- They are ready to rumble. The first Republican presidential debate is just hours away and everyone on stage has their work cut out for them.

The debate has the potential to become one of the defining moments of the 2016 election cycle. Some of the candidates need to grab the headlines and bump up name recognition. For others, the right move is simply to appear above the fray. And everyone, of course, needs to prove they know how to debate with Donald Trump on the stage.

The ABC News political team breaks down what each candidate needs to prove on Thursday night:

Jeb Bush: Could The Safe Approach Backfire?

Bush is not about saying "cute things,” a longtime adviser told ABC News, predicting he would give a solid debate performance. But given the company he will be keeping on the debate stage (he will be positioned right next to Donald Trump) Bush risks coming across as a plain vanilla candidate. The once formidable national polling lead he once had has slipped away as Trump has surged. Bush hasn't been in a debate in almost 13 years, since his last gubernatorial race in 2002. The key for him will be to prove he can be the measured alternative to the louder voices on the stage without simply being forgettable.

Ben Carson: Nice To Meet You

Carson's main focus on the debate stage will be to introduce himself to those who may not know who he is. "We think that about 50 percent of the people that will be watching have never heard of him, don't know who he is,” press secretary Deana Bass told ABC News. "So it's also important for him to first of all introduce himself to millions of Americans who will see him for the first time.” The neurosurgeon has been consistently polling in the middle tier with fellow GOPers like Huckabee, Rubio and Cruz. Carson needs to use the debate to break out of the middle of the pack.

Chris Christie: Comeback Kid

After barely claiming one of the last podiums for the first debate, Chris Christie will need to prove that he is still a viable contender for the nomination. The New Jersey governor was once considered a major player for his combative talk - and he'll need to show that he still has that blunt-style magic. But it hasn't been easy. "You can't do a mock debate here with ten folks trying to figure out who's going to say what,” he told reporters at Irish Fest in Cedar Falls, Iowa. Those close to Christie say that to be successful in the debate Christie will also need to focus on his record as governor and experience on national security issues.

Ted Cruz: Watching The Clock

What's on the line for Ted Cruz? The problem is that Cruz knows how to talk...and keep talking, famously taking the Senate floor for 21 hours to filibuster Obamacare. The Texas Senator will have to prove that he can make his point concisely and effectively and not launch into a long-winded professorial lecture. HIs colleagues have even accused Cruz of lecturing them. Still, Cruz is no stranger to the stage: he was a champion debater at Princeton and later Harvard Law School. But while he's also known for his oratorical skills, he rarely stands behind a podium. So Cruz will need to feel at home behind the podium - and with the strict time constraints.

Mike Huckabee: Broaden The Base

Mike Huckabee, who won the 2008 Iowa caucuses largely boosted by evangelical Christian voters, hopes to regain much of that support and distinguish himself from several other candidates boasting similar Christian conservative credentials. He also needs to broaden his focus beyond his white evangelical base. Campaign spokesman Hogan Gidley says he may argue his experience as Arkansas governor battling Bill and Hillary Clinton's lingering political clout and appointees uniquely qualifies him to take on Hillary Clinton in 2016.

John Kasich: Welcome to the Big Leagues

After John Kasich barely scraped by for the tenth podium in the first debate, the newcomer needs to prove he can play hardball with the other candidates who have been in the race much longer. But the Ohio governor, who hopped into the race late and has experienced a post-announcement surge in the polls, will have the advantage of debating in his home state - also raising the stakes for a successful performance. What's the bottom line? He needs to use the debate to capitalize on his climbing polling numbers and heighten his name recognition to earn a permanent place in the middle tier.

Rand Paul: Get Back On The Map

The libertarian Senator from Kentucky has one thing to prove: that he's still alive and kicking. Just a few months ago, Rand Paul had been one of the GOP's rising stars, with passionate followers and a unique brand. But he's been missing from the headlines since the onset of the campaign. He'll be trying to win them back by highlighting his outsider brand and pointing to his unique positions on issues that will distinguish him from the field. A spokesperson for the Kentucky Senator's campaign says Paul "will highlight his vision on how to keep America safe, scrap the current tax code and replace it with a 14.5 percent flat rate and protect every citizen's privacy."

Marco Rubio: The Stay Fresh Strategy

As one of the most talented communicators in the GOP field, tonight could be Rubio's moment to shine. The Florida senator's presidential bid has been all about establishing himself as the party's fresh face, and at the debate, be on the lookout for language from him that appeals to younger voters. Over the past few months, Rubio has also been reluctant to criticize fellow Republicans, arguing "one of the reasons Barack Obama is president today, is because Republicans four years ago spent all of their time ripping each other apart." But this is a debate, after all, and he will also need to prove he can throw a punch -- and that he's not too nice (or too young) to be the next president.

Donald Trump: The Devil Is In The Details

Trump is sitting atop the national polls and tonight, he will be standing at the center of the debate stage. The moderators will undoudtedly press the bombastic business mogul to go deeper on policy issues than he ever has before. On the campaign trail and in interviews, Trump insists he knows exactly how to deal with everything from immigration issues to the fight against ISIS, but so far, he has provided little in the way of specifics. The debate will test whether he can back up his rhetoric with actual ideas. But as the Donald tells it, he hasn't done much in the way of preparation: "As far as preparing for the debates I am who I am,” he recently said. "I'm not a debater I get things done.”

Scott Walker: Can He Stay Above The Fray?

As a top-tier presidential contender, Walker will be an easy target for the nine other candidates sharing the debate stage. Walker's big challenge: To stay above the fray. Walker typically takes a cautious approach handling hot button issues, sticking close to his talking points. But on debate stage, he will have to avoid looking evasive or overly scripted. In addition to proving that he can think quickly on his feet and offer satisfying responses to tough questions, Walker will have to demonstrate expertise on complex foreign policy matters, an area where he has stumbled in the past.