UPDATE: Ted Cruz was projected to win by multiple outlets but the race was still too close to call on the Democratic side as the clock struck midnight in Iowa.
Iowa voters head for the caucuses Monday night for the first major referendum of the 2016 presidential elections.
As Iowa voters consider their preferred candidates, stakes are high for contenders from both sides, who have jostled months for the lead.
On the Republican side, Sen. Ted Cruz (R-Texas) and real-estate magnate Donald Trump are locked in a battle for the top spot. Trump is hoping that his unconventional candidacy motivated new voters to turn out to vote, while Cruz is banking on the strength of his well-organized ground game in the state to help him eke out a victory.
On the left, Democratic presidential front-runner Hillary Clinton is hoping to fend off a surging Sen. Bernie Sanders (I-Vermont), who has managed to close the massive gap in support between the two candidates over the past month.
Get a closer look at Iowa:
Long-shot former Maryland Gov. Martin O'Malley (D) is also hoping that his months of attending small events and going door-to-door in the state will help him surpass low-expectations.
11:49 p.m. ET -- Sanders appeared at his headquarters close to midnight, calling the results a "virtual tie," and praising his supporters for bucking entrenched interests.
"I think the people of Iowa have sent a very profound message to the political establishment, to the economic establishment, and to the media establishment," Sanders said. "And that is given the enormous crisis facing our country, it is just too late for establishment politics and establishment economics."
Sanders also congratulated Maryland Gov. Martin O'Malley (D), who suspended his campaign Monday night and who the seantor praised for running an issue-oriented campaign.
"It's never easy to lose, I've lost more than one campaign. He should know that he contributed to the dialogue and ... won the respect of the American people."
11:29 p.m. ET -- Despite the fact that the race was still too close to call, Clinton took the stage at her headquarters in Iowa, thanking her supporters and praising Sanders for engaging in an ideoligcal debate.
"It is rare that we have the opportunity we have now. To have a real contest of ideas. To really think hard about what the Democratic party stands for and what we want the future of our country to look like if we do our part to build it," Clinton said. "I am a progressive who get's things done for people."
11:24 p.m. ET -- ABC projected that Trump secured second place in Iowa.
11:22 p.m. ET -- Cruz took the stage at his Iowa headquarters with his family and Rep. Steve King (R-Iowa), thanking Iowa voters and slamming the media.
"God bless the great state of Iowa," Cruz said.
"Iowa has sent notice that the Republican nominee and the next president of the United States will not be chosen by the media, will not be chosen by the Washington establishment, will not be chosen by the lobbyists."
11:12 p.m. ET -- After deplaning in Iowa, Cruz briefly spoke with ABC, saying that he's very pleased with his victory in Iowa.
"It was a tremendous evening, I'm very, very encouraged, very, very happy," Cruz said. "What a victory for the grassroots."
11:09 p.m. ET -- CBS reported that turnout reached record levels on the Republican side.
10:50 p.m. ET -- Trump briefly took the stage at his Iowa headquarters, saying he surprised everyone by coming in second.
"I was told by everybody 'Do not go to Iowa because you will not finish in the top ten,'" Trump said. "We finished second, and I want to tell you something: I'm honored."
Trump congratulated Cruz on his victory, and said that he loved Iowa so much he may end up buying land in Iowa.
"I think I might come here and buy a farm, I love it," Trump said.
10:48 p.m. ET -- The race on the Democratic side remains razor thin.
10:36 p.m. ET -- Rubio took the stage at his Iowa headquarters as precincts showed him with a surprisingly close third-place finish, beating some expectations.
"So this is the moment they said would never happen. For months, they told us we had no chance," Rubio said to cheers.
"For months, they told us because we didn't have the right endorsements, or the right political connections, we had no chance....They told me I needed to wait my turn."
10:30 p.m. ET -- Though most major news networks have called the Republican race in Iowa for Cruz, the Democratic race remains undecided. With 85% of precincts reporting, Sanders is less than 1 point behind Clinton.
10:27 p.m. -- Former Arkansas Gov. Mike Huckabee (R), who won the Iowa caucus in 2008, announced that he will suspend his campaign.
10:23 p.m. -- ABC and NBC both called Iowa for Cruz.
10:17 p.m. -- With almost all of the precincts reporting, according to CNN, Rubio is only 1 point behind Trump. Rubio earned 23% support, while Trump earned 24%, and Cruz appearing to close in on a lead with 28% support.
10:08 p.m. ET -- The Republican race has remained fairly stagnant, though the precincts reports caught up to the Democratic side. With 78% precincts reporting, 28% of Republicans backed Cruz, 24.4% backed Trump, and 22.8% backed Rubio.
10:02 p.m. -- Politico's Hadas Gold tweeted that Rubio has seen a large amount of traffic on his website, which could be a result of his better-than-predicted showing in Iowa.
10:06 p.m. ET -- With less than a quarter of the precincts left, Sanders is still slightly behind. Sanders racked up 49% support, with Clinton just ahead at 50.4% support.
9:58 p.m. ET -- A source close to the O'Malley campaign told Business Insider that O'Malley will suspend his campaign before the end of the evening after he failed to win any precincts.
9:55 p.m. ET -- Rubio is much closer to Trump than was projected in recent public polls. With 64% of Republican precincts reporting, Cruz garnered 28.2% support, Trump garnered 25% support, and Rubio garnered 21.9% support.
9:47 p.m ET -- Clinton's lead over Sanders has bumped back up slightly, with just over 2% separating the candidates. With 69% of precincts reporting, Clinton racked up 50.8% support, with Sanders retaining 48.6% support.
9:43 p.m. ET -- Over half of the Republican precincts have reported, showing a three-way race between Trump, Rubio, and Cruz.
9:33 p.m. ET -- As more precincts report, Cruz has maintained a steady lead. With 41% of precincts reporting, the Texas senator netted 29% support, while Trump netted 26%, and Rubio netted 20.5% support.
9:27 p.m. ET -- Retired neurosurgeon Ben Carson released a statement denying that he may suspend his campaign.
Carson Communications Director Larry Ross said that Carson needed to fly home to Florida to "get a fresh set of clothes" after the caucuses instead of moving on to New Hampshire, the next nominating state.
"Contrary to false media reports, Dr. Ben Carson is not suspending his presidential campaign, which is stronger than ever," Ross said. "After spending 18 consecutive days on the campaign trail, Dr. Carson needs to go home and get a fresh set of clothes. He will be departing Des Moines later tonight to avoid the snow storm and will be back on the trail Wednesday. We look forward to tonight's caucus results and to meaningful debates in New Hampshire and South Carolina."
9:21 p.m. ET -- With about one-quarter of the Republican precincts reporting, Cruz led slightly with 29.9% support. Trump was right behind at 26.8%, Rubio had 19%, and Carson had just under 10%.
9:18 p.m. ET -- Sanders seems to be gaining. With almost half of the precincts reporting, Sanders is now within 2-3% points of Clinton.
9:13 p.m. ET -- Politico reported that Sen. Tim Scott (R-South Carolina) will endorse Sen. Marco Rubio (R-Florida). As the third-nominating state, South Carolina is perceived as an important electoral prize.
9:10 p.m. ET -- Cruz and Trump are locked in a dead heat. With 17% of precincts reporting, Cruz attained 29.9% support, with Trump capturing 27.2%, Rubio capturing 18.9%, and Carson capturing 9.9% support.
9:06 p.m. ET -- Sanders appears to be slightly gaining on Clinton. With 34% of precincts reporting, Sanders earned 47.6% support, with Clinton ahead at 51.8% support and O'Malley staying steady at less than 1%.
In a quick interview with CNN, Sanders cautioned that it was too soon to draw conclusions from the results.
"Too early," Sanders said when asked about early precinct reports. "We will find out in an hour or so."
8:56 p.m. ET -- With 21% of caucuses reporting, Clinton earned 53%, according to The Associated Press, with Sanders close behind at 46.5% and O'Malley sinking to less than 1% support.
The Republican side has continued to lag in reporting results, with only 7% reporting an hour after the caucuses officially began.
With 7% of precincts reporting:
— Ryan Struyk (@ryanstruyk) February 2, 2016
8:48 p.m. ET -- With 13% of precincts reporting, Clinton drew 52.4% support, while Sanders drew 46.5%, and O'Malley drew 1.1%.
Republican precincts were slower to report. According to the 4% of precincts that have returned results, Cruz and Trump are running neck and neck. Cruz secured 31.1% support, with Trump netting 30% and Sen. Marco Rubio (R-Florida) netting 16%.
8:31 p.m. ET -- CNN released early entrance polls, which the network stressed likely skewed older. Clinton garnered at 50% support according to that early poll, with Sanders capturing 44% support and former Maryland Gov. Martin O'Malley (D) garnering 3%.
See photos from caucus night:
8:27 p.m. ET -- Several different candidates stopped by precincts.
Trump gave a truncated version of his stump speech at a caucus site in West Des Moines, Iowa where former Hewlett Packard CEO Carly Fiorina was also attempting to win over voters.
Carly Fiorina is at the same caucus as Trump in West Des Moines…. they’re just feet away from each other.
— Dylan Byers (@DylanByers) February 2, 2016
O'Malley (D) made a last minute stop at Drake University in Des Moines.
8:00 p.m. ET -- CNN reported promptly at 8 p.m. that early entrance polls showed Trump, Sen. Marco Rubio (R-Florida), and Sen. Ted Cruz (R-Texas) as the leaders on the Republican side, with Sanders and Clinton in a tight race on the left.
Some early reports showed that the number of first-time caucus-goers on the Democratic side was not as high as 2008, which could spell trouble for the Sanders campaign which is counting on a wave of support from new voters.
7:56 p.m. ET -- CNN reported that retired neurosurgeon Ben Carson is set to speak in Iowa potentially before all of the caucus results are in, and will fly home to Florida instead of moving on to New Hampshire, where many candidates are headed this week.
Unofficial Carson advisor Armstrong Williams said rumors that Carson may drop out were an "outright lie."
7:45 p.m. ET -- The Des Moines Register's Jennifer Jacobs reported that she's seeing "crazy amounts of new registrations" at GOP caucuses, a potentially good sign for Trump.