Des Moines, Iowa (CNN) -- From Mitt Romney's apparent growing confidence to Newt Gingrich's fading expectations, to Rick Santorum's coming under increased scrutiny, there's a new political reality in the Hawkeye State with just four days to go until the Iowa caucuses.
As six of the major Republican presidential candidates stump across Iowa on Friday, the campaign landscape has been altered. The transformation was captured by a CNN/Time/ORC International poll released Wednesday, which showed Gingrich's support among likely Iowa GOP caucus-goers plunging, one-time long-shot candidate Rick Santorum more than tripling his support since the beginning of the month, and Romney slightly edging out Rep. Ron Paul of Texas for the top spot among the field of White House contenders.
Romney starts Friday with a campaign rally in West Des Moines before heading to New Hampshire, which holds the second contest on the primary and caucus calendar. But he'll return to Iowa Saturday afternoon, and in a sign of increased confidence, a campaign aide confirmed Romney will spend caucus night in Des Moines -- instead of his firewall state of New Hampshire, where the campaign could cushion the blow of a poor Iowa showing.
"Sure, I want to win Iowa," said Romney, on the stump in Mason City, before adding modestly that "everybody wants to win Iowa. I'm not going to predict who's going to win."
Romney's events in the state the past two days have been drawing larger crowds, and a senior Romney adviser told CNN's Dana Bash that the overall mood of the campaign is "guarded, given the flux of this campaign, but in a good place."
But painful memories from four years ago temper any public signs of confidence. Romney spent a lot of time and money campaigning in Iowa in 2007, only to come in second to former Arkansas Gov. Mike Huckabee, who scored an upset victory in the caucuses. Romney then lost to Sen. John McCain, the ultimate GOP nominee, in New Hampshire, and later dropped his bid for the presidency.
The last Republican to score back-to-back victories in Iowa and New Hampshire was Gerald Ford in 1976. If Romney wins Iowa and then takes New Hampshire, where a new CNN/Time/ORC poll of likely GOP primary voters indicate he's the overwhelming front-runner, his momentum might be too much for other candidates to overcome.
If Romney is publicly downplaying expectations, Santorum is ecstatic about his surge in the polls.
"Well, I think we're doing pretty well right now. We're gonna go to New Hampshire after this," the former senator from Pennsylvania said Thursday, adding that in Iowa "it's moved pretty quickly and pretty dramatically, and we feel that can happen in New Hampshire too as well, as South Carolina, and going forward."
Santorum, who holds his first rally Friday in Ames, is aiming to capitalize on his fresh bump in the polls with a new radio ad set to air statewide. The minute-long spot, titled "Best Chance," argues that Santorum is the most electable candidate in the Republican field because he is "a full spectrum conservative" with "more foreign policy credentials than any of the candidates."
The ad closes by telling Iowa conservatives, who have long been fractured in the Republican race, that Santorum is a candidate "we can all unite behind."
While he increases his ad buys in Iowa, Santorum's campaign is scrambling to buy television time in New Hampshire. A source familiar with the move told CNN that the campaign started to make media buys in New Hampshire on Thursday, and is planning to run television and radio ads statewide beginning next Monday.
However, a rise in the polls comes with increased scrutiny from Santorum's rivals. Texas Gov. Rick Perry, who's scrambling to kick-start his campaign, launched a radio ad that attacks Santorum over his record on pork-barrel spending.
"It's 'Wheel of Washington!' I'm your host, Wink Tax-and-Spend! First question: Which Republican running for president voted for the Bridge to Nowhere earmark? Yes, Susie from Des Moines," the ad says.
"Rick Santorum?" answers Susie.
"Correct! Santorum voted for the Bridge to Nowhere and a highway bill full of pork," responds the announcer.
Santorum defended his record, telling CNN's Chief Political Correspondent Candy Crowley in an interview on "John King, USA" that "I had a great record, from the taxpayer groups and from the spending groups. Yes, did I -- did I have some earmarks? Well, if you look at the Constitution of the United States, it says that Congress spends the money. And what happened was that earmarks were abused. Not mine, but others, who did abuse the earmark process."
Gingrich, who kicks Friday off with an event in Des Moines, appears to be pulling in smaller crowds than he has in recent days. There were fewer than 70 people at his Thursday morning town hall at the Sioux City convention center. Over the last two days, he's pulled in crowds no larger than 200 at each location.
But the former House speaker has tried to pick up ground in other ways -- he's countered the millions spent on negative attack television ads by some opponents and third party groups by holding frequent telephone town halls with Iowans to clear up any distortions on his record. Gingrich said 32,000 people dialed into Wednesday night's tele-town hall and he planned to hold one every day except Sunday.
Asked if he would stay in the race if he finished fourth in Iowa, Gingrich said "Oh, sure," adding that "there's more than three tickets (out of Iowa). Considering that I'm 20 points ahead in some other states, it would be fairly foolish for me not to stay in the race. It is a long way from here to picking the nominee."
Paul, who's making his third bid for the White House, campaigns Friday across the heavily Republican northwestern part of the state. He's come under increased attack from his rivals over his stance on foreign policy and national defense. Paul spent much of Thursday defending his positions.
Rep. Michele Bachmann, who's stuck in the single digits in Iowa polling, confirmed to CNN's Wolf Blitzer Thursday that another key member of her presidential campaign was no longer working for her.
"He quit," Bachmann said of former Political Director Wes Enos. Bachmann appeared on "The Situation Room with Wolf Blitzer." The Ron Paul campaign put out a release noting that he was "recently terminated" by the Bachmann campaign.
The move is the latest development over the last day that has rocked Bachmann's Iowa organization. Late Wednesday, former Bachmann state chairman Kent Sorenson showed up on stage at an event for rival Ron Paul, declaring he had switched allegiances just days before the first-in-the-nation caucus.
Almost immediately, Bachmann claimed the move was financially motivated, citing a conversation she claimed to have had with Sorenson.
Enos released a statement early Thursday calling into question Bachmann's account of what prompted Sorenson to jump ship. Enos' statement was circulated by Paul's campaign Thursday afternoon.
"I won't say much about the situation or the conflicting statements beyond this; I can say unequivocally that Kent Sorenson's decision was, in no way financially motivated," Enos wrote in the statement.
At the time, Enos said he was sticking with Bachmann, despite their disagreement.
CNN's Paul Steinhauser, Peter Hamby, Rachel Streitfeld, Shawna Shepherd, Shannon Travis, and Kevin Liptak contributed to this report