By Corbett B. Daly

SPARTANBURG, SC - Eight candidates looking to unseat President Obama will gather on stage at Wofford College Saturday night for a debate on national security and foreign policy hosted by CBS News and National Journal.

Watch the debate live here, starting at 8:00 PM ET

Special Report: The CBS News/National Journal debate

Submit a debate question: What do you want to ask the candidates?

The Spartanburg, South Carolina, debate is chance for Texas Gov. Rick Perry to revive his candidacy after a major flub Wednesday night in Michigan where he said he wants to eliminate three government agencies but could only name two of them. The awkward pause has been played over and over again on TV and the Internet since then.

In the CBS News poll released Friday, Cain leads the field with 18 percent, followed by Romney and a surging Newt Gingrich at 15 percent. Perry is in fourth place in the poll with 8 percent, followed by Ron Paul at 5 percent, Michele Bachmann at 4 percent, Rick Santorum at 2 percent and Jon Huntsman at 1 percent.

The poll also showed that GOP primary voters consider Gingrich the presidential candidate most qualified to lead the military and handle an international crisis. He was cited by 31 percent of those surveyed, followed by Romney at 19 percent and Cain at 8 percent.

Meanwhile, political observers will be watching Herman Cain closely to see how he fares on matters of foreign policy. He has zero foreign policy experience, and may have the most to lose. Cain has been criticized as a Johnny one-note with his signature 9-9-9 tax plan and been immersed in battling sexual harassment accusations for the past two weeks. Saturday night's forum will be a signifcant test for the former restaurant executive.

Asked which GOP presidential candidate is most qualified to be commander-in-chief, Republican primary voters chose Romney more than any other candidate, at 26 percent. Gingrich took 21 percent, Cain 11 percent and Perry 9 percent. (Read more from the poll on Americans' views about foreign policy.)

CBS/NJ GOP debate tonight: 5 things to watch

South Carolina is key for Republican primary voters. Since 1980, the winner of the South Carolina primary has gone on to win the Republican nomination every time.

The race for the GOP nomination is still in flux, however. According the CBS News poll, 7 in 10 Republican primary voters say it is still too early to say for sure which candidate they will support.

Moderated by CBS Evening News anchor Scott Pelley and National Journal congressional correspondent Major Garrett, the debate airs at 8:00 p.m. ET on the CBS Television Network and will be webcast at CBSNews.com and NationalJournal.com. The final half hour will only be available online, except for the West Coast where the full debate will air on television.

After the debate, CBS News political analyst John Dickerson will host a post-debate webcast analysis of the candidates on CBSNews.com.

The debates are closely watched among Republican primary voters, 61 percent of whom said they have seen at least one in the latest CBS News poll. Slightly more than half of all voters have seen at least one debate so far.

Three in four Republican primary voters say the debate performances matter when they are deciding which candidate to back. About 30 percent said they are "very important" and another 46 percent said they are "somewhat important." About one in four voters said debate performances do not matter at all when they are choosing a candidate.

Among the questions to be answered tonight:

Can Perry clear the low bar of expectations? Will Gingrich contain himself? Can Cain get back on message? For five key things to watch, check out Jan Crawford's analysis here.

Video: What to expect in the GOP debate

What does each candidate have at stake?

Rob Hendin contributed to this story.