Former Massachusetts Governor Mitt Romney during the Iowa GOP/Fox News Debate in August, 2011. (IowaPolitics.com/Flickr)

Stating the obvious, former state Republican Party Chairman Fergus Cullen told Reuters, "The debates are their opportunity to be seen by tens of thousands of voters. They are critically important."

For one contender, New Hampshire may be something of a "gimme." Former Massachusetts Governor Mitt Romney comes into this week's primaries with a considerable lead—an NBC News/Marist poll showed he holds 42% of the vote—as well as a "bull's eye on his back," according to political analysts.

But that's nothing new, said CNN's Deputy Political Director Paul Steinhauser. "The two-time presidential candidate is used to being on the receiving end of attacks from his GOP rivals," Steinhauser said. "But this will be the first debate where Rick Santorum isn't an afterthought standing at the far edge of the stage."

There have been a number of surprising popularity shifts recently for the GOP candidate pool.

From CNN:

The former Pennsylvania senator (Santorum) has enjoyed a recent surge in campaign funding following his strong showing in Iowa and has benefited from a bump in New Hampshire support.

Still, he trails in the third spot.

Santorum's recent rise will likely force Romney to share some of the spotlight as single-digit candidates like Texas Gov. Rick Perry, who once led in the polls, take aim in a much-anticipated sparring match Saturday.

Former House Speaker Newt Gingrich, meanwhile, has watched his numbers decline since late December and will be counting on a break-out performance to stay relevant as the Republican field begins to take shape.

Ex-Utah Gov. Jon Huntsman has also staked out his claim in New Hampshire. But despite devoting the bulk of his campaign resources there, he continues to hover around 9%.

Tuesday's primary is widely thought to be a make-or-break moment for Huntsman, a former ambassador to China, who is counting on a strong showing to continue campaigning nationally.

Saturday's debate will be broadcast on ABC News from Saint Anselm College in New Hampshire at 9 p.m. ET. Candidates will then have roughly 10 hours to prepare for the 9 a.m. debate Sunday co-sponsored by NBC's Meet the Press and Facebook.

NBC is calling for question submissions via Facebook, as well as real-time feedback during Sunday's debate. Voice your own commentary on the network's Politics site here.

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