mike huckabee suspend campaign sot_00003725.jpg
PHOTO: CNN
mike huckabee suspend campaign sot_00003725.jpg
Now playing
00:50
Mike Huckabee suspends presidential campaign
Bernie Sanders speaks at the MSNBC Democratic Candidates Debate at the University of New Hampshire on February 4, 2016, in Durham, New Hampshire.
PHOTO: Justin Sullivan/Getty
Bernie Sanders speaks at the MSNBC Democratic Candidates Debate at the University of New Hampshire on February 4, 2016, in Durham, New Hampshire.
Now playing
00:57
Sanders on Iowa Caucuses: Winner doesn't take all
PHOTO: CNN
Now playing
01:30
The Democratic town hall in 90 seconds
Trump cruz tantrum dnt acosta tsr_00014617.jpg
Trump cruz tantrum dnt acosta tsr_00014617.jpg
Now playing
02:47
Donald Trump: Ted Cruz 'stole' Iowa caucuses
Now playing
02:48
Sanders, Clinton battling for Independents
Hillary Clinton: December 2014; Mitt Romney, Jan. 2015
PHOTO: Getty Images
Hillary Clinton: December 2014; Mitt Romney, Jan. 2015
Now playing
01:30
Iowa in 2012 and 2016: Two caucus cliffhangers
DES MOINES, IA - FEBRUARY 01:  Republican presidential candidate Sen. Ted Cruz (R-TX) reaches out to supporters after winning at the caucus night gathering at the Iowa State Fairgrounds on February 1, 2016 in Des Moines, Iowa. Cruz beat out businessman Donald Trump and Sen. Marco Rubio (R-FL), who finished just behind Trump.  (Photo by Christopher Furlong/Getty Images)
PHOTO: Getty Images
DES MOINES, IA - FEBRUARY 01: Republican presidential candidate Sen. Ted Cruz (R-TX) reaches out to supporters after winning at the caucus night gathering at the Iowa State Fairgrounds on February 1, 2016 in Des Moines, Iowa. Cruz beat out businessman Donald Trump and Sen. Marco Rubio (R-FL), who finished just behind Trump. (Photo by Christopher Furlong/Getty Images)
Now playing
01:59
Highlights from the Iowa night speeches
iowa caucus cnn coverage recap origwx js_00013022.jpg
iowa caucus cnn coverage recap origwx js_00013022.jpg
Now playing
02:51
Five hours of CNN's Iowa caucus coverage in 3 minutes
hillary clinton iowa caucus sot_00005814.jpg
PHOTO: CNN
hillary clinton iowa caucus sot_00005814.jpg
Now playing
01:35
Clinton: Campaign stands for what's best in America
iowa caucuses bernie sanders speech sot_00003013.jpg
iowa caucuses bernie sanders speech sot_00003013.jpg
Now playing
01:30
Bernie Sanders: We are in a virtual tie
PHOTO: CNN
Now playing
00:51
Ted Cruz: The people, not the media, pick the president
PHOTO: CNN
Now playing
01:20
Ted Cruz: Judeo-Christian values built America
PHOTO: CNN
Now playing
00:46
Donald Trump after Iowa loss: Congratulations Ted
marco rubio speaks to supporters_00011420.jpg
marco rubio speaks to supporters_00011420.jpg
Now playing
03:20
Marco Rubio speaks to his supporters in Iowa
martin omalley suspend campaign sot_00002920.jpg
PHOTO: CNN
martin omalley suspend campaign sot_00002920.jpg
Now playing
00:56
Martin O'Malley suspends presidential campaign
PHOTO: CNN
Now playing
02:51
Donald Trump thanks Iowa, congratulates opponents
Republican presidential candidate, Sen. Ted Cruz, R-Texas, speaks at Green County Community Center, Monday, Feb. 1, 2016, in Jefferson, Iowa. (AP Photo/Chris Carlson)
PHOTO: Chris Carlson/AP
Republican presidential candidate, Sen. Ted Cruz, R-Texas, speaks at Green County Community Center, Monday, Feb. 1, 2016, in Jefferson, Iowa. (AP Photo/Chris Carlson)
Now playing
01:32
Iowa caucus result: Ted Cruz projected to win
Rand Paul victory Liberty movement sot_00003925.jpg
Rand Paul victory Liberty movement sot_00003925.jpg
Now playing
00:46
Rand Paul claims a victory for the Liberty Movement
iowa caucuses hillary clinton bernie sanders entrance polls chalian ac_00001726.jpg
PHOTO: CNN
iowa caucuses hillary clinton bernie sanders entrance polls chalian ac_00001726.jpg
Now playing
00:48
Iowa caucuses: Why the Democratic race is so close
iowa caucus gop three man race blitzer king_00001009.jpg
PHOTO: CNN
iowa caucus gop three man race blitzer king_00001009.jpg
Now playing
02:12
GOP caucus votes reveal 3-man race
JOHNSTON, IA - JANUARY 31: Democratic Presidential Candidate Martin O
PHOTO: Steve Pope/Getty Images
JOHNSTON, IA - JANUARY 31: Democratic Presidential Candidate Martin O'Malley speaks to potential supporters at a residence on January 31, 2016 in Johnston, Iowa. O'Malley and other candidates are making their final appeals to voters ahead of the Iowa caucus February 1. (Photo by Steve Pope/Getty Images)
Now playing
01:15
Sources: Martin O'Malley to suspend campaign
Now playing
01:34
Iowa caucuses: Breaking down the numbers
trump leading iowa entrance polls sot ac_00011008.jpg
trump leading iowa entrance polls sot ac_00011008.jpg
Now playing
01:56
Donald Trump speaks out at Iowa caucus site
large voter turnout democrats iowa foreman sot ac_00004310.jpg
PHOTO: CNN
large voter turnout democrats iowa foreman sot ac_00004310.jpg
Now playing
01:11
Voter turnout higher than expected at Iowa caucus site
how does a caucus work iowa 2016 origwx al_00005123.jpg
how does a caucus work iowa 2016 origwx al_00005123.jpg
Now playing
01:54
Why do we care so much about the Iowa caucuses?
huckabee santorum view art and reflect iowa caucus 2016 origwx allee_00004824.jpg
huckabee santorum view art and reflect iowa caucus 2016 origwx allee_00004824.jpg
Now playing
01:46
Past Iowa winners struggle in new era
iowa ground game in the age of tump origwx GR_00000000.jpg
iowa ground game in the age of tump origwx GR_00000000.jpg
Now playing
03:11
Does the Iowa ground game matter in the age of Trump?
Vampire Weekend at Bernies
PHOTO: Jeremy Moorhead / CNN
Vampire Weekend at Bernies
Now playing
03:14
Josh Hutcherson, Vampire Weekend party for Bernie
clint howard ted cruz origwx al_00015901.jpg
clint howard ted cruz origwx al_00015901.jpg
Now playing
03:03
What Clint Howard thinks of the 2016 race
Bremer County Tuchman Pkg AC _00003221.jpg
PHOTO: CNN
Bremer County Tuchman Pkg AC _00003221.jpg
Now playing
03:08
Meet the soothsayers of American politics
iowa state profile craig robinson origwx js_00000926.jpg
iowa state profile craig robinson origwx js_00000926.jpg
Now playing
05:05
The five political regions of Iowa, explained
des moines social club Where the cool kids caucus iowa 2016 origwx allee_00000306.jpg
des moines social club Where the cool kids caucus iowa 2016 origwx allee_00000306.jpg
Now playing
01:01
Where the cool kids caucus
PHOTO: SAUL LOEB/ROBYN BECK/AFP/Getty Images
Now playing
01:53
Iowa's Evangelicals debate Trump vs. Cruz
US Republican presidential candidate Donald Trump (R) is greeted on stage by fellow Republican candidate Ted Cruz before speaking at a rally organized by the Tea Party Patriots against the Iran nuclear deal in front of the Capitol in Washington, DC, on September 9, 2015.
PHOTO: NICHOLAS KAMM/AFP/Getty Images
US Republican presidential candidate Donald Trump (R) is greeted on stage by fellow Republican candidate Ted Cruz before speaking at a rally organized by the Tea Party Patriots against the Iran nuclear deal in front of the Capitol in Washington, DC, on September 9, 2015.
Now playing
03:55
Cruz warns: If Trump wins Iowa he might be 'unstoppable'
Republican presidential candidate Sen. Marco Rubio (R-FL) speaks to guests at a town hall syle meeting on January 29, 2016 in Dubuque, Iowa.
PHOTO: Scott Olson/Getty Images
Republican presidential candidate Sen. Marco Rubio (R-FL) speaks to guests at a town hall syle meeting on January 29, 2016 in Dubuque, Iowa.
Now playing
01:28
Marco Rubio's Iowa strategy
Donald Trump (R) speaks as Rick Santorm (C) as Mike Huckabee (L) look on during a Trump campaign rally raising funds for US military veterans at Drake University in Des Moines, Iowa on January 28, 2016.
PHOTO: WILLIAM EDWARDS/AFP/Getty Images
Donald Trump (R) speaks as Rick Santorm (C) as Mike Huckabee (L) look on during a Trump campaign rally raising funds for US military veterans at Drake University in Des Moines, Iowa on January 28, 2016.
Now playing
03:18
Inside Trump's one of a kind debate counter-programming
Now playing
01:56
The Democratic town hall in under two minutes