Nearly every remaining Republican presidential candidate, save Jim Gilmore, received invitations to Saturday night's ninth GOP debate, set to take place in Greenville, South Carolina.

The Feb. 13 debate comes exactly one week before a decisive Republican primary in which an already winnowed field of seven is expected to get smaller. Mike Huckabee, Rick Santorum, and Rand Paul suspended their campaigns following the Iowa caucus, and Chris Christy and Carly Fiorina did the same after Tuesday's New Hampshire primary.

Gilmore is the only GOP candidate who didn't qualify, failing to meet any of CBS News' three prerequisites. A candidate must have finished in the New Hampshire primary's top five, placed among Iowa's top three, or averaged at least fifth place in national and South Carolina Republican presidential polls.

On Friday, CBS News announced which candidates would participate: Donald Trump, Ted Cruz, Marco Rubio, Ben Carson, Jeb Bush, and John Kasich.

Cruz Vying for South Carolina's Evangelical Vote

Cruz lost some of the momentum he garnered from his Iowa victory by finishing third in New Hampshire, one spot behind Kasich and in a virtual tie with Rubio and Bush, given that all three candidates left with three delegates apiece.

The Texas senator battled negative publicity surrounding ill-informed noticed his campaign sent Iowa voters hours before the Feb. 1 caucus. Cruz's campaign misinterpreted a CNN report stating Ben Carson was heading to Florida instead of New Hampshire. Staffers and volunteers immediately notified caucus-goers both in mailers and through phone calls despite CNN issuing a statement moments later clarifying that Carson was not dropping out of the race.

Cruz defended his campaign's actions and apologized to Carson during last Saturday's primary in the Granite State, but scorned CNN for their message. His response may have detracted undecided voters who repeatedly hear Trump boast about how superficial Cruz can be.

At the same time, New Hampshire doesn't have the large evangelical population Iowa does; one overwhelmingly in support of Cruz.

A CBS News poll released last December found registered right-leaning South Carolina voters thought Cruz was more electable than Trump by a 58-47 margin. Two-thirds of people considered themselves born-again or evangelical Christians.

While pollsters didn't ask for participants' religious affiliations, a majority of the state's residents are Protestant and may view Cruz's faith as a reason for his electability. There weren't enough Christian conservatives to win in New Hampshire, but there are more than enough in the Palmetto State.

Rubio Out to Prove He's Not a Robot Candidate

In his primary night speech last Tuesday, Rubio humbly admitted rehearsed statements and robotic responses may have cost him votes.

"I'm disappointed with tonight. But I want to tell you that disappointment is not on you. It's on me. It's on me," Rubio said, referring both to his fifth-place finish and futile attempts to defending himself during last weekend's debate. "I did not do well on Saturday night. So listen to this: that will never happen again."

Rubio drew criticism for his heated exchange with Chris Christie. Christie grilled Rubio for his inexperience and what seemed like scripted responses. Instead of going after the New Jersey governor, Rubio responded by attacking President Obama. He did so at least four times.

A New York Times exit poll found 11 percent of primary-day voters chose Rubio; just 12 percent decided to support him within the last few days. Still, 29 percent of people though Rubio could still win in November, compared to 33 percent for Trump.

The challenge Rubio has heading into Saturday's debate is convincing South Carolinians he doesn't run on canned statements. Instead of provoking candidates, Rubio plays it safe by repeating memorized sound bites. They usually revert to vilifying President Obama or retracing his Cuban-American upbringing.

Christie exposed that weakness and it may not fly under the radar this time around.

Online Viewing

CBS will are the debate, beginning at 9 p.m. EST. The network will broadcast it via its CBSN digital streaming service.