But New Hampshire is much friendlier territory for real-estate magnate Donald Trump, who heads into the votes with a commanding, double-digit lead.
In the Democratic primary, meanwhile, Sen. Bernie Sanders (I-Vermont) has continued to surge. After a narrow loss to the front-runner, former Secretary of State Hillary Clinton, in Iowa, Sanders is poised to capture victory in the Granite State. Clinton still holds a sizable, if shrinking, lead in national polls.
Here's another look at who has the best chance of making it to the White House to succeed President Barack Obama.
Our rankings are based on the Real Clear Politics averages of national polls and those in states of New Hampshire and South Carolina. We also factored in the candidates' delegate count and their finish in Iowa, as well their momentum (or lack thereof) over the past few weeks.
Since Iowa, four candidates have dropped out of the race: former Arkansas Gov. Mike Huckabee (R), Sen. Rand Paul (R-Kentucky), former Sen. Rick Santorum (R-Pennsylvania), and former Maryland Gov. Martin O'Malley (D).
Here's a look at where all the candidates stand.
All poll results as of Monday.
Feb 2016 Presidential Power Rankings
POWER RANKINGS: Here's who has the best chance at being our next president
8. Chris Christie, Republican, New Jersey governor
Christie has seen a bit of momentum sapped over the past month in the first-primary state of New Hampshire, where he is counting on a strong finish and where he has put in the most time of any GOP candidate.
Amid a barrage of attacks from rival candidates and their allied interests, Christie has seen his poll standing in the Granite State dip about six points over the past month-plus. He's now sixth there, compared with fourth last month.
He had, however, the most attention-grabbing moment of last weekend's debate, when he confronted Rubio and got the best of him during a lengthy, terse exchange. He has argued that exchange has the potential to alter the fundamentals of the race. We'll see.
National polling average among Republican voters: 2.5% (T-7th)
New Hampshire: 5.4% (6th)
South Carolina: 2.3% (6th)
Last month: 8
(Photographer: Andrew Harrer/Bloomberg via Getty Images)
6. Jeb Bush, Republican, former Florida governor
AP Photo/Charles Krupa
Bush, once viewed as the clear front-runner, has seen Trump sap the momentum he had built after his official campaign announcement in June. His poll numbers have slumped across the board — his 17% national average in July has dipped almost 13 points over the past six-plus months.
It's starting to pay off, as he has seen a slight poll bump over the past few weeks in New Hampshire, and now sits in fifth amid a crowded cluster of establishment-minded candidates.
Bush has showed, too, that he is a dynamic fund-raiser. And he retains significant resources that could prove to be a game changer in the long haul.
National polling average among Republican voters: 4.3% (5th)
New Hampshire: 11.3% (5th)
South Carolina: 10% (4th)
Last month: 5
(Photo by Scott Eisen/Getty Images)
5. Bernie Sanders, Democrat, senator from Vermont
Sanders looks poised to upset Clinton in New Hampshire — perhaps by a significant margin — a feat that was unthinkable even last summer.
Sanders is peaking at the right time. His momentum, and the grassroots support and donations behind it, have evoked comparisons to the 2008 rise of Barack Obama, then an Illinois senator.
But Sanders still faces daunting challenges against the behemoth that is Clinton and her campaign. There are questions about whether he's a legitimate threat in the long haul and about his viability as a potential nominee in a general election.
But the door to the nomination that was long thought closed could creak even more open with a strong win in New Hampshire.
National polling average among Democratic voters: 36% (2nd)
New Hampshire: 53.9% (1st)
South Carolina: 32.5% (2nd)
Last month: 6
(Photo by Andrew Burton/Getty Images)
4. Marco Rubio, Republican, senator from Florida
Rubio was perhaps the biggest winner from the Iowa caucuses, as he and his campaign played the "expectations game" perfectly and surprised with a stronger-than-expected, third-place finish right behind Trump.
He has surged in the week since. He's up more than six points nationally and about four points in New Hampshire. He looked poised for a strong second-place finish, in fact, until last weekend — when he earned brutal reviews for his debate performance.
Did his rivals bring him down a notch? Rubio's finish in New Hampshire could perhaps define the shape of the race going forward.
National polling average among Republican voters: 17.8% (3rd)
New Hampshire: 14.4% (2nd)
South Carolina: 12.7% (3rd)
Last month: 4
(Photo by Chip Somodevilla/Getty Images)
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And to the polls: Here's a look at where the candidates stand in their respective parties when combining their delegate totals and their standing in national, New Hampshire, and South Carolina polls.