The 2016 Iowa Republican presidential caucuses took place on February 1 in the U.S. state of Iowa, traditionally marking the Republican Party's first nominating contest in their series of presidential primaries ahead of the 2016 presidential election.

The Democratic Party held its own Iowa caucuses on the same day.

Ted Cruz was able to defeat Donald Trump in the Iowa Caucus by winning over Evangelical caucus-goers; Cruz won 51,666 caucus votes or 27.6%, giving him a net gain of one delegate over Trump. Cruz visited all 99 counties of Iowa and held small events. Cruz outperformed his polling average, which predicted a narrow Trump victory in the caucus.

Following poor performances in the caucuses, Rand Paul, Mike Huckabee and Rick Santorum suspended their campaigns. Both Huckabee and Santorum had previously won the caucus in 2008 and 2012 respectively.

Procedure According to the Republican Party of Iowa's bylaws, if more than one candidate is nominated at the Republican National Convention, all of Iowa's delegates are bound to vote "proportionally in accordance with the outcome of the Iowa Caucuses" on the first ballot, even if the candidate has withdrawn from the race.Article VIII, Republican Party of Iowa bylaws , amended June 27, 2015. The ballot is a blank piece of paper, and the candidates that voters may vote for in the non-binding preference poll included the following:

Jeb Bush Ben Carson Chris Christie Ted Cruz Carly Fiorina Jim Gilmore John Kasich Marco Rubio Donald Trump Rand Paul Rick Santorum Mike Huckabee

Caucus operations The caucuses began at 7:00 PM local time across 1,681 precincts statewide. After the selection of caucus chairs and secretaries, campaign representatives made speeches supporting their candidates before voters cast their preferences on paper ballots. The 2016 Republican caucuses set a new turnout record with 186,932 participants, significantly higher than the 121,503 who participated in 2012.

Campaign The Iowa caucuses required extensive ground organization and retail politics from the candidates. Ted Cruz's campaign pursued a traditional grassroots approach, completing the "Full Grassley" by visiting all 99 counties in Iowa while building relationships with evangelical and conservative leaders. His campaign utilized sophisticated data analytics and microtargeting to identify and turn out likely supporters.

Donald Trump opted for a less conventional strategy, focusing on large rallies that drew thousands of attendees across the state and earned media coverage. However, questions persisted about whether his unorthodox approach could successfully convert rally attendance into caucus participation from first-time voters.

Marco Rubio positioned himself as an electable conservative alternative, particularly appealing to suburban voters and party regulars. His campaign emphasized his youth and vision for a "New American Century," gaining momentum in the final weeks before the caucuses.

Forums and debates

November 20, 2015 – Des Moines, Iowa The Presidential Family Forum was held in the Community Choice Credit Union Convention Center in Des Moines, Iowa. Ben Carson, Ted Cruz, Carly Fiorina, Mike Huckabee, Rand Paul, Marco Rubio, and Rick Santorum attended the forum hosted by evangelical Christian advocacy group The Family Leader. It was hosted by politician and political activist Bob Vander Plaats and moderated by political consultant and pollster Frank Luntz. Protesters interrupted the beginning of the event and were removed by police.

January 28, 2016 – Des Moines, Iowa The seventh debate was the second debate to air on Fox News. As in Fox's first debate, the moderators were Bret Baier, Megyn Kelly, and Chris Wallace. This was the last debate before actual voting began with the Iowa caucuses on February 1, 2016. Due to personality conflicts with Fox News, Donald Trump opted out of the debate.

Endorsements Cruz secured several influential endorsements that proved crucial to his victory, including Congressman Steve King, who represented Iowa's 4th congressional district, and Bob Vander Plaats, president of The Family Leader, a prominent evangelical organization.

Trump notably received limited support from Iowa Republican officials, though he led most pre-caucus polls. Meanwhile, Rubio gained important momentum when he received the endorsement of the Des Moines Register and other newspapers in the closing weeks of the campaign.

Withdrawn candidates

Polling

Aggregate polls +Source of poll aggregationDates administeredDates updatedMarco RubioDonald TrumpTed CruzMarginRealClearPoliticsRealClearPoliticsuntil February 1, 2016February 1, 201616.9%28.6%23.9%Trump +4.7FiveThirtyEightFiveThirtyEightuntil February 1, 2016February 1, 201618.1%25.6%24.3%Trump +1.3 Poll source Date 1st 2nd 3rdOtherCaucus resultsCaucus resultsFebruary 1, 2016 Ted Cruz27.64% Donald Trump24.30% Marco Rubio23.12% Ben Carson 9.30%, Rand Paul 4.54%, Jeb Bush 2.80%, Carly Fiorina 1.86%, John Kasich 1.86%, Mike Huckabee 1.79%, Chris Christie 1.76%, Rick Santorum 0.95%, Jim Gilmore 0.01%, Other 0.06%Emerson College Margin of error: ± 5.6% Sample size: 298 January 29–31, 2016Donald Trump27.3%Ted Cruz25.6% Marco Rubio21.6% Mike Huckabee 4.7%, Jeb Bush 3.8%, John Kasich 3.8%, Rand Paul 3.4%, Ben Carson 3.4%, Chris Christie 3.2%, Carly Fiorina 1.7%, Rick Santorum 0.5%, Undecided 1%Quinnipiac University Margin of error: ± 3.3% Sample size: 890January 25–31, 2016Donald Trump31% Ted Cruz24% Marco Rubio17% Ben Carson 8%, Jeb Bush 4%, Rand Paul 4%, Mike Huckabee 3%, Carly Fiorina 2%, John Kasich 2%, Chris Christie 1%, Rick Santorum 1%, Jim Gilmore 0%, Not decided 3%Opinion Savvy Margin of error: ± 3.2% Sample size: 887 January 29–30, 2016Donald Trump20.1%Ted Cruz19.4%Marco Rubio18.6% Ben Carson 9.0%, Rand Paul 8.6%, Jeb Bush 4.9%, Mike Huckabee 4.4%, John Kasich 4.0%, Carly Fiorina 3.8%, Chris Christie 3.0%, Rick Santorum 2.1%, Undecided 2.2%Des Moines Register/Bloomberg/Selzer Margin of error: ± 3.5% Sample size: 602 January 26–29, 2016Donald Trump28% Ted Cruz23% Marco Rubio15% Ben Carson 10%, Rand Paul 5%, Chris Christie 3%, Jeb Bush 2%, Mike Huckabee 2%, Carly Fiorina 2%, John Kasich 2%, Rick Santorum 2%, Jim Gimore 0%, Undecided 2%, Uncommitted 3%Public Policy Polling Margin of error: ± 3.5% Sample size: 780 January 26–27, 2016Donald Trump31% Ted Cruz23% Marco Rubio14% Ben Carson 9%, Jeb Bush 4%, Mike Huckabee 4%, Rand Paul 4%, Carly Fiorina 3%, John Kasich 2%, Chris Christie 2%, Rick Santorum 1%, Jim Gimore 1%, Undecided 2%NBC/WSJ/Marist Margin of error: ± 4.8% Sample size: 415 January 24–26, 2016Donald Trump32% Ted Cruz25% Marco Rubio18% Ben Carson 8%, Jeb Bush 4%, Carly Fiorina 2%, John Kasich 2%, Rand Paul 2%, Chris Christie 2%, Mike Huckabee 2%, Other 0%, Undecided 3%Monmouth University Margin of error: ± 4.4% Sample size: 500 January 23–26, 2016Donald Trump30% Ted Cruz23% Marco Rubio16% Ben Carson 10%, Jeb Bush 4%, Rand Paul 3%, John Kasich 3%, Mike Huckabee 3%, Chris Christie 2%, Carly Fiorina 2%, Rick Santorum 1%, Jim Gilmore 0%, Other 0%, Undecided 3%ARG Margin of error: ± 5.0% Sample size: 400 January 21–24, 2016Donald Trump33% Ted Cruz26% Marco Rubio11% Ben Carson 7%, Chris Christie 4%, Rand Paul 4%, Jeb Bush 3%, John Kasich 3%, Mike Huckabee 2%, Rick Santorum 1%, Carly Fiorina 1%, Jim Gilmore 0%, Other 1%, Undecided 5%Quinnipiac University Margin of error: ± 3.8% Sample size: 651January 18–24, 2016Donald Trump31%Ted Cruz29% Marco Rubio13% Ben Carson 7%, Rand Paul 5%, Jeb Bush 4%, Chris Christie 3%, Mike Huckabee 2%, Carly Fiorina 1%, John Kasich 1%, Jim Gilmore 0%, Rick Santorum 0%, Not decided 2%ISU/WHO-HD Margin of error: ± ?% Sample size: 283 January 5–22, 2016Ted Cruz25.8% Donald Trump18.9% Ben Carson13.4% Marco Rubio 12.3%, Rand Paul 6.9%, Jeb Bush 3.8%, Mike Huckabee 3.7%, Carly Fiorina 1.1%, Rick Santorum <1%, Chris Christie <1%, John Kasich <1%Fox News Margin of error: ± 5.0% Sample size: 378 January 18–21, 2016Donald Trump34% Ted Cruz23% Marco Rubio12% Ben Carson 7%, Rand Paul 6%, Chris Christie 4%, Jeb Bush 4%, John Kasich 2%, Mike Huckabee 2%, Rick Santorum 2%, Carly Fiorina 1%, Other 1%, Don't Know 2%CBS/YouGov Margin of error: ± 5.9% Sample size: 492 January 18–21, 2016Donald Trump39%Ted Cruz34% Marco Rubio13% Ben Carson 5%, Rand Paul 3%, Chris Christie 2%, Jeb Bush 1%, John Kasich 1%, Carly Fiorina 1%, Mike Huckabee 0%, Jim Gilmore 0%, No Preference 0%Emerson College Margin of error: ± 5.9% Sample size: 271 January 18–20, 2016Donald Trump33.1% Ted Cruz22.8% Marco Rubio14.2% Ben Carson 9.1%, Chris Christie 5.4%, Jeb Bush 5.1%, John Kasich 2.9%, Rand Paul 2.7%, Carly Fiorina 2.1%, Mike Huckabee 1.7%, Undecided 1%CNN/ORC Margin of error: ± 6.0% Sample size: 266 January 15–20, 2016Donald Trump37% Ted Cruz26% Marco Rubio14% Ben Carson 6%, Jeb Bush 3%, Mike Huckabee 3%, Rand Paul 2%, Carly Fiorina 1%, Rick Santorum 1%, Chris Christie 1%, John Kasich 1%Monmouth College/KBUR/Douglas Fulmer & Associates Margin of error: ± 3.7% Sample size: 687 January 18–19, 2016Ted Cruz27%Donald Trump25% Ben Carson11% Marco Rubio 9%, Jeb Bush 7%, Chris Christie 4%, Mike Huckabee 4%, Rand Paul 3%, John Kasich 3%, Carly Fiorina 3%, Rick Santorum 1%, Jim Gilmore 1%, Undecided 4%Loras College Margin of error: ± 4.4% Sample size: 500 January 13–18, 2016Donald Trump26%Ted Cruz25% Marco Rubio13% Ben Carson 8%, Jeb Bush 6%, John Kasich 4%, Chris Christie 3%, Mike Huckabee 3%, Rand Paul 3%, Carly Fiorina 2%, Rick Santorum 1%, Undecide 7%Public Policy Polling Margin of error: ± 4.3% Sample size: 530 January 8–10, 2016Donald Trump28%Ted Cruz26% Marco Rubio13% Ben Carson 8%, Jeb Bush 6%, Chris Christie 3%, Carly Fiorina 3%, Mike Huckabee 3%, John Kasich 3%, Rand Paul 3%, Rick Santorum 2%, Jim Gilmore 0%, Undecided 2%DM Register/Bloomberg Margin of error: ± 4.4% Sample size: 500 January 7–10, 2016Ted Cruz25%Donald Trump22% Marco Rubio12% Ben Carson 11%, Rand Paul 5%, Jeb Bush 4%, Chris Christie 3%, Mike Huckabee 3%, Carly Fiorina 2%, John Kasich 2%, Rick Santorum 1%ARG Margin of error: ± 4.0% Sample size: 600January 6–10, 2016Donald Trump29%Ted Cruz25% Marco Rubio10% Ben Carson 8%, Chris Christie 6%, Rand Paul 4%, Jeb Bush 3%, John Kasich 3%, Mike Huckabee 2%, Rick Santorum 2%, Carly Fiorina 1%, Other 1%, Undecided 5%Quinnipiac University Margin of error: ± 4.0% Sample size: 602January 5–10, 2016Donald Trump31%Ted Cruz29% Marco Rubio15% Ben Carson 7%, Chris Christie 4%, Jeb Bush 3%, Mike Huckabee 3%, Rand Paul 2%, John Kasich 2%, Carly Fiorina 1%, Rick Santorum 1%, Not decided 5%Fox News Margin of error: ± 4.0% Sample size: 504January 4–7, 2016Ted Cruz27%Donald Trump23% Marco Rubio15% Ben Carson 9%, Jeb Bush 7%, Rand Paul 5%, Chris Christie 4%, Mike Huckabee 2%, Carly Fiorina 1%, John Kasich 1%, Rick Santorum 1%, Other 1%, Undecided 2%NBC/WSJ/Marist Margin of error: ± 4.6% Sample size: 456January 2–7, 2016Ted Cruz28%Donald Trump24% Marco Rubio13% Ben Carson 11%, Rand Paul 5%, Jeb Bush 4%, Chris Christie 3%, Carly Fiorina 3%, Mike Huckabee 2%, John Kasich 2%, Other 1%, Undecided 3%

Poll source Date 1st 2nd 3rdOtherGravis MarketingGravis Marketing Margin of error: ± 5.0% Sample size: 440 December 18–21, 2015Donald Trump31%Ted Cruz31% Marco Rubio9% Ben Carson 7%, Jeb Bush 4%, Mike Huckabee 4%, Carly Fiorina 3%, Chris Christie 2%, John Kasich 2%, George Pataki 1%, Lindsey Graham 1%, Rand Paul 1%, Rick Santorum 0%, Unsure 5%CBS News/YouGovCBS News/YouGov Margin of error: ± 5.3% Sample size: 1252 December 14–17, 2015Ted Cruz40% Donald Trump31% Marco Rubio12% Ben Carson 6%, Jeb Bush 2%, Rand Paul 2%, Carly Fiorina 2%, Mike Huckabee 2%, Chris Christie 1%, John Kasich 1%, Rick Santorum 1%, Lindsey Graham 0%, Jim Gilmore 0%, George Pataki 0%, No preference 0%Public Policy PollingPublic Policy Polling Margin of error: ± 4.3%