By MICHAEL FALCONE ( @michaelpfalcone ) and AMY WALTER ( @amyewalter )

DES MOINES - Isn't it ironic? The two candidates who start caucus day with the best shot at finishing at the head of the pack are also the two candidates who have taken polar-opposite approaches to winning Iowa.

First, there's former Pennsylvania Senator Rick Santorum, who over the past few months has put down roots in the state so deep he might as well be an honorary resident. Santorum has visited all of Iowa's 99 counties - many of them more than once - and by his campaign's count, held roughly 380 events.

As far as Iowa is concerned, he's earned a reputation as the hardest working candidate in presidential politics. And, if he finishes in the top two or three, it will be a combination of his relentless courtship of Iowans and his appeal to social conservatives that helped drive his last-minute surge.

"The people of Iowa, New Hampshire, and South Carolina have not only made me a better candidate, not only will they make be a better president, but they've made me a better person," Santorum said at his final campaign stop yesterday in Altoona, telling a crowd that packed into a Pizza Ranch restaurant that if they help him to a strong finish in the caucuses. "You will not only shock this country, but you will shock the world."

Then there's Mitt Romney, who has covered more ground in Iowa this week than he has during the rest of the primary season combined. Over the past seven days Romney has logged well over a thousand miles, crisscrossing the state in a bus emblazoned with three words "Conservative, Businessman, Leader."

Those words have been the crux of his message to the Republican electorate here and they've been resonating. But up until this week, Romney took a cautious approach to the state, popping in for a handful of quick visits and spending only a fraction of the time and money here that he did four years ago.

His campaign staff masterfully managed expectations right up to the point when they saw his numbers rising. Then he went all in. And last night he even predicted a win.

"We're gonna win this thing with all of our passion and strength and do everything we can to get this campaign on the right track to go across the nation and to pick up other states and to get the ballots I need and the votes I need to become our nominee," Romney said at an appearance in Marion, Iowa. (Still playing the expectations game, the Romney campaign said the candidate was referring to winning the nomination, not Iowa.)

Romney is running a disciplined race here and nationally, and if he winds up on top tonight, it will also be because he had a little help from his opponents. His biggest potential foes, Rick Perry and Newt Gingrich are on political life support. They could come back to life in South Carolina, but it's going be hard to do.

Why? One reason is because Gingrich will continue to direct his own campaign operation. Sure, he could hurt Romney by running a slew of "contrast" ads against him in New Hampshire and South Carolina. But he's just as likely to veer woefully off course.

Gingrich told ABC's Jonathan Karl yesterday that he'll be going up with ads "explaining" his relationship with Freddie Mac. As the old saying goes: If you're explaining you're losing.

Even so, Romney is likely to end this process right where he started it: unable to prove he can capture more than roughly a quarter the vote and keeping alive the question: Can he win in a place like South Carolina or Florida if the field is thinned out and the conservative vote isn't as divided?

ABC's David Muir sat down with Romney in Iowa yesterday. Can the former Massachusetts governor seal the deal? WATCH: http://abcn.ws/sMy6FQ

ABC's George Stephanopoulos interviewed Rick Santorum today on "Good Morning America." The former senator predicted, "we're going to do very well." WATCH: http://abcn.ws/tSOYpF and http://abcn.ws/vcXGW4

 

ABC EXCLUSIVES:

SANTORUM EXPLAINS 2006 LOSS. In an interview with ABC's Jake Tapper yesterday, Rick Santorum explained away his 2006 Senate loss, saying it was a historically bad year for Republicans who lost control of both houses of Congress. "It was the worst election year for republicans in the history of the state, this isn't going to be 2006," said Santorum, who stopped between campaign stops in Iowa to talk to ABC News. "If I was the only guy that loss and everybody else won you could say that, oh well, that guy is in trouble, we stood up and didn't flinch. We stood up and said this is what we believed the problem are… I was prepared to stand up and fight for what I believed in, and I wasn't supposed to win any of the elections I ever ran, and I won the first four against odds no one would have ever taken. And they were decent election years, some good, some not so good. We were able to win those elections in heavily democratic districts, because we stood up for what we believed in, and you know what and when that went south in a big way we lost, its ok, this is not that election year." http://abcn.ws/uEZLfJ Watch Tapper's "World News" report on Santorum, ascendant: http://abcn.ws/t3JZir

DOES RON PAUL SEE HIMSELF IN THE OVAL OFFICE? 'NOT REALLY.' An amazing admission last night from Ron Paul. In an exclusive interview, ABC's Terry Moran asked him: "When you lay your head on your pillow at night, do you see yourself in the Oval Office?" "Not really," he said. He went on to say that he's not blind to the odds, but they are "not as slim as they were 25 years ago." Hard to imagine any other candidate saying that. Moran also asked if he thought he was too old to be president. He'd be 81 at the end of his first term. He said, "Freedom is a youthful idea," his health is good, and he challenges any of his rivals to a physical fitness test. He also jokingly accused Moran of ageism."Be careful," he said. "There are laws against that." http://abcn.ws/sMToSW

THE NEW NEWT. No more Mr. Nice Guy.  Newt Gingrich will "draw a very clear contrast" with Romney "every day" immediately after today's caucuses, the former House speaker told ABC News' Jonathan Karl. "Everything we say will have Romney's quote, Romney's videotape, Romney's record; it'll all be based explicitly on Romney," Gingrich said in an interview in Independence, Iowa yesterday. Gingrich has said repeatedly that Republicans should aim their attacks at President Obama, not fellow Republicans.  But after getting hammered by millions of dollars in negative ads, Gingrich says he will now return fire, targeting Romney over and over again. "He set the tone of the campaign," Gingrich said.  "By going after me negatively and dishonestly." But won't his plan violate Gingrich's promise to run a positive campaign? "Well, if the facts are negative, then that tells you about his career," Gingrich said. http://abcn.ws/t74YBa

DEMOCRATIC COUNTER-PROGRAMMING. Democratic National Committee Chair Debbie Wasserman Schultz and Iowa Congressman Bruce Braley join forces for a press conference to frame today's caucuses. According to a DNC advisory, they'll talk about how "the GOP candidates continue to move to increasingly extreme policy positions" and how "Mitt Romney continues to hide from his record, which includes balancing the state budget on the backs of the middle class as governor of Massachusetts and flip-flopping on everything from guns and abortion to taxes and immigration." Wasserman Schultz and Braley will hold a press conference at 10 a.m. CT at the Renaissance Des Moines Savery Hotel.

@ woodhouseb : DNC Chair  @DWStweets speaks with the NBC affiliate in Des Moines at Java Joes.  #IACaucus yfrog.com/ntrvttyj

GOP PUSHBACK. Republican National Committee Chairman Reince Priebus pens an Op-Ed in the Des Moines Register laying out the stakes: "It was exactly four years ago, on a cold Iowa night, that Barack Obama boldly promised, 'Years from now, when we've made the changes we believe in … you'll be able to look back with pride and say that this was the moment when it all began.' Today, the president has made the changes he believes in, yet we look back not with pride, but with painful regret. Over the coming weeks and months, the national conversation will understandably swirl around the race for the Republican nomination. As our candidates travel the country, they will share their visions for America's future. But as they do, we cannot for a moment lose sight of our present reality - the reality that demands we elect a new leader to the White House, one capable of charting a roadmap to restoring our economic security." http://dmreg.co/vAJZv3

 

ABC'S CRYSTAL BALL. We're journalists, not prognosticators. But in this business, sometimes it is just an irresistible conversation line to turn to each other and ask, 'so, what do you think is really going to happen?' Monday morning on "Good Morning America," Matthew Dowd and George Stephanopoulos put it out there. Dowd says he thinks Rick Santorum is going to snag first place in Tuesday's Iowa Caucus.  That's a big prediction for a candidate who was trailing in last place in the polls just a few weeks ago.  George predicts Romney will take first in the Caucus, but he says he "wouldn't be surprised by Ron Paul or Santorum." Here are more predictions about caucus night from ABC's political team: http://abcn.ws/vM1sWW

 

THE BUZZ

MITT ROMNEY RALLY GETS OCCUPIED. A dispatch from ABC's Emily Friedman from Clive, Iowa: For the first time since launching his presidential campaign, Mitt Romney got a visit from Occupy Wall Street protestors during a rally Monday night just outside Des Moines, Iowa. Midway through his stump speech, Romney was interrupted by protestors shouting their rallying cry, "Mic check!" Nearly immediately, the protestors were drowned out by cheers from the crowd of more than 500 with chants of "Mitt! Mitt! Mitt!"  One member in the crowd screamed back at the protestors, "Get a job!" Romney, audibly laughing at the outspoken crowd member, addressed the protestors. "Thanks guys, let's talk about the Constitution again," said Romney. But the protestors kept chanting, "Stop the war on the poor! Stop the war on the poor!" "Thanks guys," Romney responded again, looking around as security escorted the individuals outside. "Isn't it great to live in a country where people can express their views?" http://abcn.ws/tKHXor

RICK PERRY SAYS HE'S ON A MARATHON COURSE. Reflecting on his struggles to gain traction in Iowa polls in the days leading up to the caucuses, Texas Gov. Rick Perry, an avid athlete, compared his campaign to a marathon with Iowa being the first mile of the race, ABC's Arlette Saenz report.s "This is the first, let's say, mile one of the marathon and I've run a marathon before, and I felt great at mile one and, as a matter of fact, I felt pretty great at mile 17 and 18," Perry said today at a meet and greet at the Stoney Creek Inn here. "At mile 21, you kind of start hitting that wall a little bit, and we'll see who's still running at mile 21. I finished my marathon, and I expect to finish this marathon as well." http://abcn.ws/sir5E3

IOWA BY THE NUMBERS. "As of tonight's caucus, the six leading GOP candidates have spent 354 days in the Hawkeye State, according to calculations from the Des Moines Register, and traveled more than 23,000 miles," ABC's Elizabeth Hartfield, Chris Good and Shushannah Walshe note. "In addition to their time, candidates spent big money in Iowa. They or the super PACs supporting them have spent $12.5 million and counting on television ads in the state, according to firms that track advertisements. That number breaks down to $104 spent per Republican caucus-goer on ads, based off of the estimated 120,000 caucus-goers who turned out in 2008. Candidates have taken different approaches in the state. Frontrunner Mitt Romney logged 771 miles in Iowa in just three days - beginning Jan. 1 and ending today. Interestingly enough, the former Massachusetts governor has spent the least amount of days campaigning in the state -  just 18, not including this evening's voting contest. Michele Bachmann, who is trailing in the polls, visited all 99 counties in the state in an 11-day span, during which she traveled roughly 6,200 miles and distributed 5,000 lawn signs." http://abcn.ws/ufK12T

VIDEO OF THE DAY: Rick Santorum's Wife Breaks Down in Iowa: Karen Santorum cries as husband discusses death of son Gabriel: http://abcn.ws/tBNKbl

DEMOCRATS RAKE IN CASH FOR GOVERNORS' RACES. "After a year that saw Republican governors engage in high-profile fights with unionized state employees, the Democratic Governors Association (DGA) announced Tuesday that it raised $20 million in 2011," reports ABC's Chris Good. "The DGA, the Democratic Party group that raises and spends money to elect Democratic governors, topped its fundraising in recent years with similarly few gubernatorial races. Last year saw four races, with Democrats winning in Kentucky and West Virginia and losing in Mississippi and Louisiana. In 2007, which saw three gubernatorial contests, the DGA raised $12.7 million. The 2011 haul still puts the DGA far behind its GOP counterpart. The Republican Governors Association, which typically outpaces the DGA in fundraising, announced in July that it had raised $22.1 million in the first six months of 2011." http://abcn.ws/rKnxxl

WHO'S TWEETING?

@ globeglen : IOWA CAUCUSES: Ron Paul supporter has harsh words for Romney, media in final Caucus Diary video…  bo.st/tCWXf

@ BenjySarlin : I see my news feed on Facebook is left-leaning 20somethings defending their Ron Paul endorsements…it must be caucus day!

@ AmyEGardner : Callista Gingrich, America's Camilla Parker-Bowles:  wapo.st/tTiDxg @SheThePeople

@ mattklewis : If Romney wins Iowa and N.H., he will have earned just 1% of the delegates needed to be the GOP nominee - dailycaller.com/2012/01/02/thi…

@ mollyesque : 13 degrees in Des Moines. Waiting for Mitt.  pbckt.com/pT.Q42ybs

 

GOOD MORNING IOWA. Don't forget to check The Note blog one last time for the latest edition of "Good Morning Iowa" - a one-stop-shop tip-sheet covering everything you need to know on caucus day, reported by ABC's Shushannah Walshe.

DISPATCHES FROM THE TRAIL. Also, keep an eye on our new political website OTUSNews.com ( www.Otusnews.com) The Note ( http://abcnews.go.com/blogs/politics/the-note/) and on ABC News/Politics ( http://abcnews.go.com/politics) and follow our reporters in the field on Twitter:

 

Michele Bachmann : ABC's Russell Goldman ( @GoldmanRussell )

Newt Gingrich : ABC's Elicia Dover ( @EliciaDover )

Jon Huntsman and New Hampshire: ABC's Susan Archer ( @TheOnlyArcher )

Ron Paul : ABC's Jason Volack ( @Jason_Volack )

Rick Perry : ABC's Arlette Saenz ( @ArletteSaenz )

Mitt Romney : ABC's Emily Friedman ( @EmilyABC )

Rick Santorum and Iowa: ABC's Shushannah Walshe ( @shushwalshe )

 

Check out The Note's Futures Calendar:  http://abcn.ws/ZI9gV

 

* Get  The Note delivered  to your inbox every day.

* For breaking political news and analysis check out The Note blog:  http://blogs.abcnews.com/thenote/ and ABCNews.com/Politics:  http://abcnews.com/politics