CNN's John King traveled across Iowa ahead of the caucuses there on Monday. See his full recap on "Inside Politics" Sunday at 8 a.m. ET
6 keys to the Iowa caucuses
Davenport, Iowa — There will be a lot of passion vs. organization talk in the final countdown to the Iowa caucuses: Can the palpable energy of the Bernie Sanders campaign overcome the superior nuts-and-bolts organizing of the Hillary Clinton operation?
Scott County in eastern Iowa is a good place to watch this play out. Team Clinton thought it was well organized here in 2008, and poised for a strong showing. Instead, then-Sen. Barack Obama won big, with 48% of the vote and Clinton a distant second at 29%.
Norm Bower hopes to avoid a repeat of the 2008 feeling. A volunteer at the Clinton Davenport office, he said things are more professional, and cutting edge this time in part because so many Obama campaign veterans are with Clinton this time.
Bower is confident the 2016 Clinton operation will meet or exceed its vote target here. Is it enough? His memory of how he knew in 2008 is vivid.
Iowa City, Iowa — Many candidates are organizing Iowa's college students, but none show anywhere near the boisterous energy of "Students for Rand."
And it's hard to dispute that Rand Paul has a hip campaign store with branded items aimed at younger voters and libertarians who in the past backed the Kentucky senator's father, Ron Paul.
"Rand Paul's core constituency is what we would call the 'leave me alone' coalition," said Steve Grubbs, the veteran Iowa GOP strategist leading Paul's Iowa effort.
Ron Paul got 22% of the vote here four years ago and finished a strong third place. Grubbs believes those votes are underrepresented in Iowa polls now. Plus, with colleges in session for this year's caucuses, "Students for Rand" set a 10,000-student target. One person involved said they are short of that, but in the still-impressive 6,000 range.
If Grubbs' math is correct, and caucus turnout is at traditional levels, he believes Paul could be the surprise here and climb into the top tier. If not, there will be pressure on Paul to call it quits because his Kentucky Senate seat is also up this year.
Cedar Rapids, Iowa —There is zero doubt Marco Rubio is on the rise as the Iowa campaign winds down. But how high can he climb?
The answer lies in the suburbs around Des Moines, and to the east around Davenport and Cedar Rapids. More simply put: Rubio needs the Mitt Romney map.
Yes, he hopes to cut into the Cruz campaign's evangelical base. And Rubio hopes to get a fair slice of the younger voters from Iowa's colleges and universities. But his foundation is the mainstream Republican areas that were Romney's base in both 2008 and 2012.
Donald Trump is one obstacle. The billionaire businessman is drawing votes across the spectrum -- and across the map -- in Iowa. And Rubio and his team are working feverishly in the final days to sway more establishment voters now in the Trump camp.
But there is another, significant obstacle as Rubio canvasses the Romney map: Jeb Bush. The Bush campaign working the same turf -- and the same voter lists, and the size of former Florida governor's slice of the vote Monday night will go a long way in determining the strength of the Rubio close.
Thompson, Iowa — It has the feel of a nostalgia tour by a memorable band of yesteryear: familiar words, old friends, but smaller crowds and more gray hairs.
But 2008 Iowa GOP winner Mike Huckabee isn't ready to admit he isn't going platinum this year. And, significantly, the new lyrics in this stump speech are aimed almost entirely at the candidate atop the charts at the moment with Iowa evangelicals: Ted Cruz.
Thompson is in rural Winnebago County, near the Iowa-Minnesota border, a place of farmers and hunters where Huckabee won big in 2008. As he retraces those glory days now, he constantly raises the Texas senator's opposition to government rules that benefit Iowa's ethanol industry. And, in a dig at the Canadian-born Cruz, he notes that he shares a hometown with Bill Clinton -- removing any doubt about his eligibility to be president.
To be sure, Huckabee isn't going to win this time, even if he gets all 18 votes in the room at this stop. But to ignore him is to forget the importance of the math on the margins. In this crowded field, Huckabee, Rick Santorum and Ben Carson are fighting for votes that likely otherwise would go overwhelmingly to Cruz. The higher they go, the harder it is for Cruz to pull away.
Washington, Iowa — Pastor Joseph Brown welcomes all to the Marion Avenue Baptist Church, though he readily concedes he is at a loss to understand some of his flock these days.
From the pulpit, he preaches the "sacred duty" to attending the caucuses. And once off, he plugs for Cruz and shakes his head in disbelief at the number of Christian conservatives who profess their support for Trump.
"Donald Trump is a wolf in sheep's clothing -- and evangelicals know what that means," Brown told CNN during a visit to his church. "He has stood for everything that we have been against."
Brown leads a group call 99 Pastors -- a minister organizing for Cruz in each of Iowa's counties. Membership is closer to 200 now, and Cruz urged the group in a recent meeting to do more to stop Trump, believing his inroads among evangelicals would make the difference in who wins the first vote of 2016.
Brown said the group hopes to turn out 30,000 voters for Cruz statewide. His personal goal is 600 in Washington County, which Ron Paul won four years ago with fewer than 300 votes. If the pastors succeed, Cruz will be tough to beat.
Denver, Iowa — Shane Bohlmann has a personal filter for the things "Don" said that his wife finds over the line.
"He's not verbally correct on all things," said Bohlmann, a real estate manager who has never caucused before but is now organizing for Trump in Denver, Iowa's growing "Mile Wide City" not far from Waterloo.
A Trump visit to Iowa a few months ago triggered Bohlmann's interest.
For Carter Nordman, the affection for Trump began years ago in the family living room in Adel.
"My entire family loved 'The Apprentice,' loved watching it," Nordman said. "He's an extremely intelligent, successful man."
Back then, Nordman was 10, sitting in front of the television. Now, he is ready to cast his first vote -- for Trump.
But, like Bohlmann, he is taking it another step and organizing. Nordman leads Iowa's Students for Trump, which targets college students but also high-schoolers like Nordman who are old enough to caucus.
Trump has celebrity on his side and an Iowa team with past caucus experience. But the key caucus night for Trump could well be whether these newcomers succeed in getting a wave of new voters to show up Monday.