Continued.
A country under attack
Many Americans are deeply frightened by the recent spate of terrorist attacks around the world and wonder whether Obama is doing enough to keep the country safe. Trump's explosive proposals to increase surveillance of mosques, keep a database of Muslim-Americans and enforce a temporary "ban" on Muslims entering the country have energized his supporters.
Brothers Ernie Martin and Lee Walter from Cresco, Iowa, were among a group of zealous Trump fans at the front of the line outside a Trump rally in Des Moines on December 11. They had waited more than seven hours to see the candidate in person.
"Hey, hey. Ho, ho. All the Muslims have to go!" Walter, a 64-year-old retired factory worker, began to chant.
Just days before, Trump -- who had already said he would implement a national database to register Muslims in the United States -- had put out a startling press release: a call for a "total and complete shutdown of Muslims entering the United States."
The proposal marked one of the most striking examples of Trump's penchant for forceful national security rhetoric and came on the heels of two deadly events that shifted the course of the 2016 race: the terrorist attacks in Paris that killed 130 people in November, followed by a shooting in San Bernardino, California, a few weeks later that left 14 people dead.
It drew swift and widespread condemnation, including from some of Trump's fellow GOP rivals and the Muslim-American community.
But at Trump rallies, the proposal resonated in a different way.
Just hours after Trump made the controversial announcement, his supporters -- waiting to hear him speak in Mount Pleasant, South Carolina, said they were fully on board.
"I don't want them here," Ed Campbell said. "Who knows what they're going to bring into this country?"
The mass shooting in San Bernardino marked a turning point -- the first real evidence that ISIS could also kill on American soil. Trump seized on deep-seated fears about the country coming under siege, labeling himself the "most military person there is" and vowing to "bomb the sh—out of ISIS."
Bickie Mason, a contractor from Lyman, South Carolina, who attended Trump's Spartanburg rally in November, said he felt he didn't have a choice but to agree with Trump's idea of tracking Muslim-Americans through a national database.
"I don't believe all Muslims are bad. But anybody can turn bad, and you've got to be able to locate them and know where they're at," said Mason, 64.
Trump's Muslim ban has unleashed more visceral reactions, including unambiguously hostile views toward Islam.
His supporters across the country -- from Iowa to New Hampshire to South Carolina -- told CNN in interviews they simply believe Islam is not a peaceful religion.
"Islam is not a religion. It's a violent blood cult. OK?" said Hoyt Wood, a 68-year-old military veteran waiting to hear Trump speak aboard the U.S.S. Yorktown in Mount Pleasant, South Carolina. "All they know is violence, that's all they know."
At the same rally, 55-year-old Susan Kemmelin said, "We can't look at a Muslim and tell if they're a terrorist or friendly."
Robert Engelkes, a 45-year-old corn and soybean farmer from Dike, Iowa, pointed out that there is historical precedent for targeting one group.
"What did we do in World War II? We put all the Japanese in internment camps," said Engelkes, who was standing outside a Trump event in Des Moines. "We had to do something with them."
Donald Trump: A candidate like we've never seen before
Trump has mesmerized voters. People say they have never seen a presidential candidate like Trump: He's unfiltered; he's anti-establishment; he exudes confidence and strength; he's not a politician.
If anything has been more surprising than Trump's endurance this election cycle, it's the seemingly fierce loyalty of his supporters.
It began in June with just a few hundred people crammed into the shiny lobby of Trump Tower in midtown Manhattan, there to witness Trump finally confirm the rumors -- he was indeed running for president.
When he hit the campaign trail, the crowds quickly swelled.
Thousands were soon turning up at school gymnasiums, auditoriums and local event halls to see Trump in person, forming long, winding lines that often spilled into overflow rooms. In the first weeks and months of Trump's campaign, plenty of attendees admitted they were there to catch a glimpse of the former host of the "The Apprentice" -- maybe even shake hands with the TV star.
But as the 69-year-old New Yorker rose to the top of the GOP pack, voters -- along with many in the media who had assumed the Trump campaign would be short-lived --started to reassess the unlikely presidential candidate.
Trump's colorful off-the-cuff speeches and forceful message on immigration and national security were reverberating. The curious, star-struck observers increasingly gave way to fans eager to pledge their support to the political newcomer.
Nicomi Kloempken, a Trump supporter at a Raleigh, North Carolina, campaign event in early December, put it bluntly: "He seems to just not give a f---, you know what I mean?"
That attitude would propel Trump from one controversy to the next, starting on Day One.
Rather than turn supporters off, each inflammatory statement only seemed to reinforce Trump's novelty and appeal.
Curt Handschug, an independent voter from Columbus, Ohio, who voted for Barack Obama in 2012, said he believes 2016 is the year of "Donald Trump or nobody." Trump's willingness to speak the truth, he said, set him apart from politicians.
"Sometimes he'll say things, and I'll go, 'Oh gosh, seriously?' But at least he's willing to say it," Handschug said at a Trump rally in November. "All these politicians are afraid to tell the truth."
And next to a GOP field crowded with governors, senators and ex-politicians, Trump's successful business career is a refreshing contrast.
"I like him because he's a businessman. He does what he says he's going to do. I've seen him lose a ton of money and bounce back," said Trump supporter Linda Wilkerson at a Raleigh campaign event. "We're in terrible financial debt. I hope he can bail us out."
Trump took the lead as the candidate most trusted to handle the economy last summer, and continues to dominate the field on the issue. According to the latest CNN/ORC polling, 57% of Republican voters nationally say they trust Trump over the rest of the field on the economy. In Iowa, he holds nearly a 40-point lead over Cruz as more trusted to handle the economy, 54% to 16%, and in New Hampshire, a CNN/WMUR poll finds 48% say they trust Trump most, while no other candidate tops 7%.
If Trump goes all the way to the general election, he would be the first businessman who has never held public office to win the GOP nomination since Wendell Willkie in 1940.
"With his background, he's going to put the economy back where it belongs," said Jamie Peckham, another Trump fan at the same Raleigh event.
Trump is also attracting a small but enthusiastic contingent of teenagers.
Turner Eakins and two of his friends from Millard North High School, drove from Omaha, Nebraska, to a Trump rally in Council Bluffs, Iowa, at the end of December. Marveling at the candidate's authenticity and disregard for political correctness, the three teens told CNN they all plan to cast their first votes for Trump this year.
"Politics is supposed to be boring," said Eakins, who will turn 18 by primary day. "So when three 18-year-old kids are driving out 30 minutes to go to a Trump rally, I mean -- that's a movement."
The protesters
Who are they? Why are they so upset with Trump? How does Trump's rhetoric about minorities in the U.S. make them feel? And why have recent protests become increasingly ugly and even violent?
Trump was in the middle of boasting about his latest poll numbers. "We're winning all over the country," he boomed at a November campaign rally in Birmingham, Alabama.
Then he noticed the commotion on the floor of the packed convention hall -- another protester was trying to interrupt his speech. "Get 'em the hell out of here," Trump said, waving his hand dismissively.
This outburst would turn out to be a little different from other protests at Trump rallies because a CNN reporter was filming the crowd's violent reaction to the protester. The grainy cell phone footage showed angry Trump fans pushing, kicking and jeering at the man, who at one point was lying on the ground.
The 31-year-old Black Lives Matter activist, Mercutio Southall, told CNN afterwards that the people around him had called him "monkey" and the N-word.
"I got punched in the face, I got punched in the neck. I got kicked in the chest. Kicked in the stomach. Somebody stepped on my hand," he said.
While the Birmingham incident marked one of the first times that a physical altercation was captured on camera and widely viewed, it was hardly the first time that this kind of raw anger had boiled over at a Trump rally, pitting protesters against Trump fans.
On October 10, two Asian female high school students took off their tops at a Trump rally in Norcross, Georgia, revealing writing on their bare chest and stomach: "LEGAL IMMIGRANT"; "offense taken"; "F--- TRUMP"; "WOMEN SHAMER"; "RACIST PIG."
Their yelling infuriated the people around them. Some started to shout: "Anchor babies! Go home!" Others shoved Trump campaign posters at the women and used the signs to block cameras, cheering when the hecklers were finally escorted out of the building.
"I was actually an immigrant myself nine years ago from South Korea, and Trump's beliefs on minorities, it's just ridiculous," Yu Jin Kim, one of the two women, told CNN outside. "Would you really want the next president to be racist and disregard a third of the country?"
Sara Park, whose parents are immigrants, said she was there to "stand up for the community who can't stand up for themselves."
Protests have become a common occurrence at Trump campaign rallies, fueled by the candidate's explosive statements about minority groups.
At a campaign rally in Rock Hill, South Carolina, this month, a Muslim woman wearing a hijab stood up in silent protest as Trump spoke about the hidden presence of ISIS among Syrian refugees.
As Rose Hamid was escorted out of the building, one person shouted: "You have a bomb, you have a bomb."
Several days later, at another Trump event in Clear Lake, Iowa, there were mixed reactions to Hamid's removal from the event.
"If she was asked to sit down and she didn't, well, out she goes," said John Dusheck, a 63-year-old Trump supporter from Ventura, Iowa.
"She wasn't causing any troubles," said Steven Ziller, a farmer from Belmond. "That was not right."
Civil rights activist Jesse Jackson, who has watched these events with interest from afar, said he fears that Trump is in the process of unleashing long-running "ignorance, fear and hatred in our country."
"He's tapped into a certain macho factor in the white community and it works for him. I know it's dangerous," said Jackson, a former presidential candidate. "You have the anti-immigrant, anti-refugee component to this. Them versus us. Anti-Muslim."
Ali Ali attended a December 5 Trump rally in Spencer, Iowa. He said he was born in the African nation of Djibouti and grew up in fear of persecution, until he came to the United States as a refugee.
The 50-year-old Muslim-American said he knew he didn't belong in that crowd -- "You can see, I'm the only Muslim of 3,000 people today in Spencer," he said -- but felt that by being in the same room as Trump, he might get a chance to share his grievances.
Being Muslim today is not easy, Ali told CNN, and Trump wasn't making it any easier.
"I'm a safe guy. I don't have no bomb. I never killed nobody. So I don't want to be labeled a terrorist," he said.
Trump's rhetoric about Muslims, including his support for a database to track Muslim-Americans, is no different from the persecution of Jews decades ago, Ali said.
"They're doing to Muslims today what they (did) to Jewish (people) in 1938," he said. "My name is Ali Ali, I'm from Shakopee, Minnesota, and my ID number: registration 00001. That will be me."
Tom LoBianco, Jeff Simon, Randi Kaye and Jennifer Agiesta contributed to this report.