The debate was already highly anticipated. The GOP race hit South Carolina in a flurry of insults, negative ads and suggestions of dirty tricks.
Donald Trump and Ted Cruz have each tasted victory in the GOP presidential race claiming the anti-establishment mantle -- Trump coasted to victory in New Hampshire this week, and Cruz won the Iowa caucuses.
Marco Rubio and Jeb Bush are hoping to have strong showings in this conservative state that can boost their momentum heading into a dozen contests on March 1 known as the "SEC primary." John Kasich, coming off a second-place showing in New Hampshire, has an uphill climb but is getting more attention of late. And if Ben Carson is going to make a move, now is the time.
Here is what to watch for in the debate at 9 p.m. ET on CBS:
Who should replace Justice Scalia? And when?
The death of Scalia, appointed by President Ronald Reagan and a conservative stalwart on the court, is a political earthquake.
Already, presidential candidates such as Cruz and Hillary Clinton were noting that the next president may have three or four chances to nominate Supreme Court justices. Now, in the middle of a presidential race, candidates will be asked who should replace Scalia, and what kind of litmus tests they would place on a nominee.
For Republicans, beyond opposing Roe v. Wade, that means candidates will have to go on the record about social issues such as gay marriage, access to contraception and the death penalty, just to name a few. Anything they say could be critical for winning the nomination — and for the general election.
The immediate question for candidates: Should the GOP-controlled Senate allow a vote on a nominee from President Barack Obama to replace Scalia? After the news broke late Saturday afternoon, Cruz and Rubio said the next president should get to make the nomination, and Senate Majority Leader Mitch McConnell agreed.
"The American people should have a voice in the selection of their next Supreme Court Justice," McConnell said in a statement. "Therefore, this vacancy should not be filled until we have a new president."
Can Rubio shake off the last debate?
The Sunday after the last Republican debate in New Hampshire, a clip of Rubio's performance saturated the airwaves, playing on repeat on the morning shows and throughout the day.
Unfortunately for the Florida senator, it was because he had stumbled -- big time.
In one of the most memorable debate moments of the 2016 election, Chris Christie delivered accused his rival of never having made a consequential decision as senator, and painted Rubio as a DC-insider who spouts one memorized talking point after another.
Rubio, as though on cue, repeated several times -- almost word-for-word -- a statement about how President Obama was purposefully taking the country down a wrong path.
"There it is," Christie said. "The memorized 25-second speech."
Rubio was widely criticized for the exchange, and in the days following the debate, protesters dressed up as robots appeared at Rubio events to mock the incident.
Coming just two days ahead of primary day, the debate no doubt hurt Rubio. He came in at fifth place right behind Jeb Bush, winning just 11% of the votes in New Hampshire.
Rubio himself admitted that his performance in the state was a disappointment. On Saturday, he'll need to demonstrate that he's put last weekend's flop squarely behind him -- and certainly avoid repeating the same, practiced lines.
As for Christie? He dropped out of the race Wednesday.
Which Donald Trump will show up?
Trump has lashed out as his rivals that stand in his way in his quest for the White House.
And yet, after notching his first in New Hampshire this week, Trump signaled that he's ready to try a different tack. The campaign pulled an attack ad against Cruz, replacing it with a positive spot. Campaign manager Corey Lewandowski said the campaign was focused on running a "positive campaign
This could prove to be a short-lived strategy.
Trump's rivals have shown no signs of letting up on the real estate developer as they prepare for a fierce battle in South Carolina. Cruz, for example, is on the air in the Palmetto State with multiple attack ads, including a new spot that accuses Trump of a "pattern of sleaze
And South Carolina just happens to be famous for its negative -- and often deeply personal -- politics.
On Friday, Trump took to Twitter to vent at Cruz: "If @tedcruz doesn't clean up his act, stop cheating, & doing negative ads, I have standing to sue him for not being a natural born citizen."
Cruz in full firing mode
Cruz is holding nothing back.
The Texas senator has released a series of attack ads in recent days aimed at Trump and Rubio. With a victory in Iowa and third-place finish in New Hampshire under his belt, Cruz badly wants a strong performance in this conservative state and is particularly eager to keep Rubio's momentum in check.
His tactic in going after both Trump and Rubio has been to question his rivals' conservative credentials. An ad titled "Conservatives Anonymous" shows a group of people sitting in a circular therapy session to discuss their disappointment over having supported Rubio. One person accuses Rubio of having "cut a deal on amnesty."
"Maybe you should vote for more than just a pretty face next time," one woman says. (The Cruz campaign pulled this ad
after it was revealed that one of the actors in the spot is a soft-core porn star).
One of the latest ads aimed at Trump
focuses on the businessman's support for eminent domain -- a practice in which the government seizes private property that many conservatives are not fond of. The narrator in this ad accuses Trump of having ""bankrolled politicians to steamroll the little guy -- a pattern of sleaze stretching back decades."
All of this suggests that a feistier and more aggressive Cruz may take the debate stage Saturday.
Family matters for Bush
South Carolina is a state that gave victories to both George H.W. Bush and George W. Bush. And now, Jeb Bush is hoping to continue the family's winning streak here next Saturday.
But achieving that will be an uphill climb for the latest Bush to run for president.
In a cycle overwhelmingly dominated by two anti-establishment candidates, the former Florida governor has struggled to vault himself to the top-tier of the crowded GOP field. The closest thing to victory that Bush has experienced this cycle was on Tuesday in New Hampshire, when he came in at fourth place in the GOP contest there. He was virtually tied with Marco Rubio and trailed behind Trump, Cruz and Kasich.
But coming in second or third place within the establishment lane is far less acceptable for Bush here in South Carolina than in New Hampshire. He is hoping that his family name will be a plus in this southern state, and in North Charleston on Monday, Bush will have his brother, George W. Bush, campaigning next to him for the first time.
Saturday, expect to hear Bush make an explicit case for why he is the best to take on Trump or Cruz -- and even remind people of his family's history of winning here.
"He's the last Republican that was president. He is the most popular Republican alive," Bush told reporters Thursday. "He has made tough decisions as president. All of that, I think, is important for people to be reminded of."
Winning the military and veterans' votes
Two constituencies in South Carolina will be key in determining the winner of the GOP South Carolina primary: military personnel and veterans.
The state is home to more than 400,000
veterans and some 38,000
active duty military members, according to recent estimates.
That means issues like national security, military spending and the treatment of veterans are likely to be front and center at Saturday's debate. And the candidates on the debate stage have their share of vulnerabilities.
For Trump, it may be a comment he made about John McCain on the campaign trail -- questioning the former GOP presidential nominee's status as a Vietnam War hero -- that could come back to haunt him.
Cruz has already come under fire from his rivals for voting for a budget that would have cut military spending. The Texas senator has hit back at that charge by pointing out that he supported an amendment to boost military spending.
Kasich's past support for closing military facilities is also likely to be met with disapproval in a state that has eight military bases.
Meanwhile, Bush is hoping that the endorsement from Sen. Lindsey Graham -- along with George W. Bush, who is popular in South Carolina, hitting the trail for him -- can win him points with the influential veterans and military community.