As the fight to win the 2016 presidential election heats up, here is a guide to who may be the next president of the United States:

Republican Nominee

Donald Trump

Trump is the son of Fred Trump, a wealthy real estate developer. Donald Trump is a successful businessman in his own right. Trump has flirted with running in the past and appeared at multiple Conservative Political Action Conferences. His brash personality and wealth make him one of the most well-known figures in the country. Although he was a Republican before 1999, Trump was a registered Democrat from 2001-2009 and previously supported universal healthcare. He was the host of "The Apprentice," a reality show on NBC.

Policy Positions:

  • Wants to build a wall across the Mexican border, and would increase fees on border crossing cards, temporary visas and entry at border ports to pay for it.
  • Would suspend immigration from regions of the world "that have a history of exporting terrorism."
  • Wants to reform income taxes into three brackets at 12, 25 and 33 percent and increase the standard deduction as part of his comprehensive tax reform plan.

Age on Election Day: 70

Education: Wharton School of the University of Pennsylvania (Economics)

Family: Married (Ivana [divorced], Marla [divorced], Melania), five children (Donald, Ivanka, Eric, Tiffany, Barron)

Birthplace: New York, N.Y.

Current Residence: New York, N.Y.

Religion: Presbyterian

Caucus and Primary Results: Iowa (2nd), New Hampshire (1st), South Carolina (1st), Nevada (2nd); Alabama (1st), Alaska (2nd), Arkansas (1st), Georgia (1st), Massachusetts (1st), Minnesota (3rd), Oklahoma (2nd), Tennessee (1st), Texas (2nd), Vermont (1st), Virginia (1st); Kansas (2nd), Kentucky (1st), Louisiana (1st), Maine (2nd); Hawaii (1st), Idaho (2nd), Michigan (1st), Mississippi (1st); Florida (1st), Illinois (1st), Missouri (1st), North Carolina (1st), Ohio (2nd); Arizona (1st), Utah (3rd); Wisconsin (2nd); New York (1st); Connecticut (1st), Delaware (1st), Maryland (1st), Pennsylvania (1st), Rhode Island (1st); Indiana (1st). Was presumptive GOP nominee for remaining primaries.

Democratic Nominee

Hillary Clinton

Voters are familiar with Clinton from her time as secretary of state, 2008 presidential campaign and time in the U.S. Senate from 2000 through 2008. Her husband, Bill, is obviously pretty famous too. After a lengthy FBI investigation into her email practices while Secretary of State, the FBI decided not to recommend indictment. The FBI did release plenty of evidence that will be fodder for Republicans this campaign season.

On July 12, Bernie Sanders officially endorsed Clinton for president. "She will be the Democratic nominee for president and I intend to do everything I can to make certain she will be the next president of the United States," Sanders said. Clinton was endorsed by President Obama and Vice President Biden on June 9.

Policy Positions:

  • Would raise taxes on the wealthy with a 4 percent surtax on incomes over $5 million.
  • Wants comprehensive immigration reform that would create a pathway to full citizenship for eligible citizens. She supports President Obama's executive actions on immigration, known as DACA and DAPA.
  • Supports tuition-free public colleges for in-state students whose family income is no more than $125,000 a year.

Age on Election Day: 69

Education: Wellesley College (Political Science), Yale University Law School (J.D.)

Family: Married (Bill), one child (Chelsea)

Birthplace: Chicago, Ill.

Current Residence: Chappaqua, N.Y. or Washington, D.C.

Religion: Methodist

Caucus and Primary Results: Iowa (1st), New Hampshire (2nd), Nevada (1st), South Carolina (1st); Alabama (1st), Arkansas (1st), Colorado (second), Georgia (1st), Massachusetts (1st), Minnesota (2nd), Oklahoma (2nd), Tennessee (1st), Texas (1st), Vermont (second), Virginia (1st); Kansas (2nd), Louisiana (1st), Nebraska (2nd); Maine (2nd); Michigan (2nd), Mississippi (1st); Florida (1st), Illinois (1st), Missouri (1st), North Carolina (1st), Ohio (1st); Arizona (1st), Idaho (2nd), Utah (2nd); Alaska (2nd), Hawaii (2nd), Washington (2nd); Wisconsin (2nd); Wyoming (2nd); New York (1st); Connecticut (1st), Delaware (1st), Maryland (1st), Pennsylvania (1st), Rhode Island (2nd); Indiana (2nd); West Virginia (2nd); Kentucky (1st or 2nd), Oregon (2nd); California (1st), Montana (2nd), New Jersey (1st), New Mexico (1st), North Dakota (2nd), South Dakota (1st)

Click here for our guide to eight of the many third-party presidential nominees, from the Libertarian Party to the Green Party to the Prohibition Party.

Past Candidates

Republicans

Click here for our guide on which 2016 Republican candidates have endorsed Trump, which say they won't vote for him and which are still undecided.

Jeb Bush

Status: Dropped out. Bush ended his campaign on Feb. 20 after failing to break into the top tier of candidates in South Carolina. He had led many national and New Hampshire primary polls in early 2015 before Donald Trump launched his campaign.

Delegates: 4

Endorsed: Ted Cruz

Caucus and Primary Results: Iowa (6th), New Hampshire (4th), South Carolina (4th)

Debates: Qualified for Aug. 6 main debate (polled in 2nd place), Sept. 16 main debate (2nd), Oct. 28 main debate (3rd), Nov. 10 main debate (5th), Dec. 15 main debate (5th), Jan. 14 main debate (5th), Jan. 28 main debate (5th), only Feb. 6 debate (5th) and the only Feb. 13 debate (5th)

Ben Carson

Status: Dropped out. Carson ended his campaign on March 4 while addressing the Conservative Political Action Conference. He led national polls briefly in November 2015 but struggled when votes were cast. Despite staying in the race through Super Tuesday, Carson never finished better than fourth in a primary or caucus and had just more than one percent of the delegates awarded so far.

Delegates: 9

Endorsed: Donald Trump

Caucus and Primary Results: Iowa (4th), New Hampshire (8th), South Carolina (6th), Nevada (4th); Alabama (4th), Alaska (4th), Arkansas (4th), Georgia (4th), Massachusetts (5th), Minnesota (4th), Oklahoma (4th), Tennessee (4th), Texas (5th), Vermont (5th), Virginia (5th)

Debates: Qualified for Aug. 6 main debate (polled in 5th place), Sept. 16 main debate (4th), Oct. 28 main debate (2nd), Nov. 10 main debate (2nd), Dec. 15 main debate (2nd), Jan. 14 main debate (4th), Jan. 28 main debate (2nd), only Feb. 6 debate (4th), only Feb. 13 debate (4th) and the only Feb. 25 debate (5th). He qualified for the only March 3 debate (4th) but chose to skip it.

Chris Christie

Status: Dropped out. Christie ended his campaign on Feb. 10 after disappointing finishes in Iowa (two percent) and New Hampshire (seven percent). He was actually one of a few candidates who led national and New Hampshire polls prior to 2015 when formal campaigning began, but he couldn't turn that early support into votes when the time came.

Endorsed: Donald Trump

Caucus and Primary Results: Iowa (10th), New Hampshire (6th)

Debates: Qualified for Aug. 6 main debate (polled in 9th place), Sept. 16 main debate (10th) and Oct. 28 main debate (8th). Did not qualify for Nov. 10 main debate (9th). Qualified for Dec. 15 main debate (7th), Jan. 14 main debate (5th), Jan. 28 main debate (6th) and only Feb. 6 debate (6th)

Ted Cruz

Status: Dropped out. Cruz ended his campaign on May 3 after failing to win the Indiana primary. It was mathematically impossible for Cruz to get a majority of delegates before the convention, but still possible to keep Donald Trump from earning a majority.

Delegates: 565

Vice Presidential Pick: Carly Fiorina

Caucus and Primary Results: Iowa (1st), New Hampshire (3rd), South Carolina (3rd), Nevada (3rd); Alabama (2nd), Alaska (1st), Arkansas (2nd), Georgia (3rd), Massachusetts (4th), Minnesota (2nd), Oklahoma (1st), Tennessee (2nd), Texas (1st), Vermont (4th), Virginia (3rd); Kansas (1st), Kentucky (2nd), Louisiana (2nd), Maine (1st); Hawaii (2nd), Idaho (1st), Michigan (2nd), Mississippi (2nd); Florida (3rd), Illinois (2nd), Missouri (2nd), North Carolina (2nd), Ohio (3rd); Arizona (2nd), Utah (1st); Wisconsin (1st); New York (3rd); Connecticut (3rd), Delaware (3rd), Maryland (3rd), Pennsylvania (2nd), Rhode Island (3rd); Indiana (2nd)

Debates: Qualified for Aug. 6 main debate (polled in 6th place), Sept. 16 main debate (5th), Oct. 28 main debate (6th), Nov. 10 main debate (4th), Dec. 15 main debate (3rd), Jan. 14 main debate (2nd), Jan. 28 main debate (2nd), only Feb. 6 debate (2nd), only Feb. 13 debate (2nd), only Feb. 25 debate (2nd), only March 3 debate (2nd) and only March 10 debate (2nd)

Carly Fiorina

Status: Dropped out. Fiorina announced she was ending her campaign on Feb. 10, after getting no more than four percent in Iowa or New Hampshire. "I will continue to travel this country and fight for those Americans who refuse to settle for the way things are and a status quo that no longer works for them," Fiorina said in a statement on Facebook. Although Fiorina had surged to third place in national polls at one point in fall 2015, her support dwindled by the time votes were cast.

Delegates: 1

Endorsed: Ted Cruz (later picked as his vice presidential candidate)

Caucus and Primary Results: Iowa (7th), New Hampshire (7th)

Debates: Did not qualify for Aug. 6 main debate (polled in 14th place). Qualified for Sept. 16 main debate (11th), Oct. 28 main debate (4th), Nov. 10 main debate (6th) and Dec. 15 main debate (6th). Did not quality for Jan. 14 main debate (9th) or Jan. 28 main debate (10th). Did not qualify for the Feb. 6 debate (8th)

Jim Gilmore

Status: Dropped out. Gilmore ended his campaign on Feb. 12, saying "I will continue to do everything I can to ensure that our next president is a free-enterprise Republican who will restore our nation to greatness and keep our citizens safe." He was only able to earn 145 votes combined in Iowa and New Hampshire. Gilmore's candidacy was so unlikely to succeed that many polls simply did not include him as an option.

Caucus and Primary Results: Iowa (12th), New Hampshire (9th)

Debates: Did not qualify for Aug. 6 main debate (polled in 17th place). Did not qualify for either Sept. 16 debate (17th), either Oct. 28 debate (15th), either Nov. 10 debate (15th), either Dec. 15 debate (14th) or either Jan. 14 debate (12th). Did not qualify for Jan. 28 main debate (11th). Did not qualify for the Feb. 6 debate (9th) or the Feb. 13 debate (7th)

Lindsey Graham

Status: Dropped out. Graham suspended his campaign in a video message released Dec. 21, saying many of the other candidates had adopted his defense policy views. During his campaign, Graham never received more than two percent support in a national, Iowa or New Hampshire poll.

Endorsed: Jeb Bush, then Ted Cruz

Debates: Did not qualify for Aug. 6 main debate (polled in 15th place), Sept. 16 main debate (16th) or Oct. 28 main debate (14th). Did not qualify for either Nov. 10 debate (13th). Did not qualify for Dec. 15 main debate (13th)

Mike Huckabee

Status: Dropped out. Huckabee ended his campaign on Feb. 1, after a poor finish in the Iowa Caucuses. After winning there in 2008, Huckabee came 10th in 2016. May 2015 was the last time Huckabee earned double-digit support in a national primary poll.

Delegates: 1

Endorsed: Donald Trump (after he was the presumptive nominee)

Caucus and Primary Results: Iowa (9th)

Debates: Qualified for Aug. 6 main debate (polled in 4th place), Sept. 16 main debate (7th) and Oct. 28 main debate (7th). Did not qualify for Nov. 10 main debate (9th), Dec. 15 main debate (10th), Jan. 14 main debate (10th) or Jan. 28 main debate (8th)

Bobby Jindal

Status: Dropped out. Jindal suspended his campaign on Nov. 17 in a Fox News interview. After entering the race, Jindal never received more than two percent in a national or New Hampshire primary poll. He peaked at seven percent in one Iowa poll.

Endorsed: Marco Rubio

Debates: Did not qualify for Aug. 6 main debate (polled in 13th place), Sept. 16 main debate (14th), Oct. 28 main debate (12th) or Nov. 10 main debate (12th)

John Kasich

Status: Dropped out. Kasich's campaign ended on May 4 after coming third in Indiana. Cruz had dropped out the night before, all but ending hopes of stopping Trump from getting a majority of delegates before the convention. Despite staying in the race nearly two months longer than Rubio, Kasich still had 18 fewer delegates than Rubio.

Delegates: 153

Caucus and Primary Results: Iowa (8th), New Hampshire (2nd), South Carolina (5th), Nevada (5th); Alabama (5th), Alaska (5th), Arkansas (5th), Georgia (5th), Massachusetts (2nd), Minnesota (5th), Oklahoma (5th), Tennessee (5th), Texas (4th), Vermont (2nd), Virginia (4th); Kansas (4th), Kentucky (4th), Louisiana (4th), Maine (3rd); Hawaii (4th), Idaho (4th), Michigan (3rd), Mississippi (3rd); Florida (4th), Illinois (3rd), Missouri (3rd), North Carolina (3rd), Ohio (1st); Arizona (4th, behind Rubio, even though Rubio had already dropped out), Utah (2nd); Wisconsin (3rd); New York (2nd); Connecticut (2nd), Delaware (2nd), Maryland (2nd), Pennsylvania (3rd), Rhode Island (2nd); Indiana (3rd)

Debates: Qualified for Aug. 6 main debate (polled in 10th place), Sept. 16 main debate (9th), Oct. 28 main debate (8th), Nov. 10 main debate (7th), Dec. 15 main debate (7th), Jan. 14 main debate (8th), Jan. 28 main debate (7th), only Feb. 6 debate (7th), only Feb. 13 debate (6th), only Feb. 25 debate (4th), only March 3 debate (5th) and only March 10 debate (4th)

George Pataki

Status: Dropped out. Pataki started calling supporters in New Hampshire on Dec. 29 to tell them he was ending his campaign. Pataki never received more than three percent in a national poll, one percent in an Iowa poll or two percent in a New Hampshire poll.

Endorsed: Marco Rubio, then John Kasich

Debates: Did not qualify for Aug. 6 main debate (polled in 16th place), Sept. 16 main debate (15th) or Oct. 28 main debate (12th). Did not qualify for either Nov. 10 debate (14th). Did not qualify for Dec. 15 main debate (12th)

Rand Paul

Status: Dropped out. Paul announced he was ending his campaign on Feb. 3, saying "I will continue to carry the torch for Liberty in the United States Senate and I look forward to earning the privilege to represent the people of Kentucky for another term." Paul led some national and New Hampshire GOP polls in 2013 and 2014 but lost traction in 2015.

Delegates: 1

Endorsed: Paul's staff says he won't endorse anyone during the primary, but he plans to endorse the eventual GOP nominee.

Caucus and Primary Results: Iowa (5th)

Debates: Qualified for Aug. 6 main debate (polled in 8th place), Sept. 16 main debate (8th), Oct. 28 main debate (8th), Nov. 10 main debate (8th) and Dec. 15 main debate (7th). Did not qualify for Jan. 14 main debate (7th) and declined to participate in the undercard. Qualified for Jan. 28 main debate (8th)

Rick Perry

Status: Dropped out. Perry ended his campaign on September 11 in a speech in St. Louis, making him the first candidate to drop out. It was reported that Perry's campaign had laid off much of its staff and was running low on funds.

Endorsed: Ted Cruz

Debates: Did not qualify for Aug. 6 main debate (polled in 11th place) or Sept. 16 main debate (12th)

Marco Rubio

Status: Dropped out. Rubio ended his campaign on March 15 after failing to win his home state of Florida and finishing last in the other four primaries that day. During primary season, Rubio only won in Minnesota, Puerto Rico and Washington, D.C. He exited the campaign with 169 delegates to his name.

Delegates: 171

Caucus and Primary Results: Iowa (3rd), New Hampshire (5th), South Carolina (2nd), Nevada (2nd); Alabama (3rd), Alaska (3rd), Arkansas (3rd), Georgia (2nd), Massachusetts (3rd), Minnesota (1st), Oklahoma (3rd), Tennessee (3rd), Texas (3rd), Vermont (3rd), Virginia (2nd); Kansas (3rd), Kentucky (3rd), Louisiana (3rd), Maine (4th); Hawaii (3rd), Idaho (3rd), Michigan (4th), Mississippi (4th); Florida (2nd), Illinois (4th), Missouri (4th), North Carolina (4th), Ohio (4th)

Debates: Qualified for Aug. 6 main debate (polled in 6th place), Sept. 16 main debate (6th), Oct. 28 main debate (3rd), Nov. 10 main debate (3rd), Dec. 15 main debate (4th), Jan. 14 main debate (3rd), Jan. 28 main debate (3rd), only Feb. 6 debate (3rd), only Feb. 13 debate (3rd), only Feb. 25 debate (3rd), only March 3 debate (3rd) and only March 10 debate (3rd)

Rick Santorum

Status: Dropped out. Santorum announced he was ending his campaign on Feb. 3 after a poor Iowa finish. Santorum is the only candidate to participate in every undercard debate. Since the start of 2015, he never received more than six percent support nationally, in Iowa or in New Hampshire.

Endorsed: Marco Rubio

Caucus and Primary Results: Iowa (11th)

Debates: Did not qualify for Aug. 6 main debate (polled in 12th place), Sept. 16 main debate (13th), Oct. 28 main debate (11th), Nov. 10 main debate (11th), Dec. 15 main debate (11th), Jan. 14 main debate (11th) or Jan. 28 main debate (11th)

Scott Walker

Status: Dropped out. Walker suspended his campaign on September 21 with a press conference in Madison, Wis. Some of Walker's major donors had announced they would start giving money to other candidates, and others had doubts about his campaign's leadership.

Endorsed: Ted Cruz

Debates: Qualified for Aug. 6 main debate (polled in 3rd place) and Sept. 16 main debate (3rd)

Democrats

Lincoln Chafee

Status: Dropped out. Chafee withdrew from the campaign on Oct. 23, in a speech at the National Issues Conference of the Women's Leadership Forum. Chafee's name was mispronounced as he took the stage. He received more than 2 percent support in just three national, Iowa or New Hampshire primary polls.

Martin O'Malley

Status: Dropped out. After a very poor finish in Iowa, Martin O'Malley decided to end his campaign on Feb. 1. He got less than one percent support in the Iowa Caucuses. In more than two years of polling the Democratic presidential primary, O'Malley never reached double-digit support in national polls.

Caucus and Primary Results: Iowa (third)

Bernie Sanders

Status: Sanders endorsed Clinton at a Clinton campaign rally in New Hampshire on July 12, effectively ending his campaign. He finished 359 pledged delgates behind Clinton, but she also had 554 more superdelegates.

Caucus and Primary Results: Iowa (2nd), New Hampshire (1st), Nevada (2nd), South Carolina (2nd); Alabama (2nd), Arkansas (2nd), Colorado (1st), Georgia (2nd), Massachusetts (2nd), Minnesota (1st), Oklahoma (1st), Tennessee (2nd), Texas (2nd), Vermont (1st), Virginia (2nd); Kansas (1st), Louisiana (2nd), Nebraska (1st); Maine (1st); Michigan (1st), Mississippi (2nd); Florida (2nd), Illinois (2nd), Missouri (2nd), North Carolina (2nd), Ohio (2nd); Arizona (2nd), Idaho (1st), Utah (1st); Alaska (1st), Hawaii (1st), Washington (1st); Wisconsin (1st); Wyoming (1st); New York (2nd); Connecticut (2nd), Delaware (2nd), Maryland (2nd), Pennsylvania (2nd), Rhode Island (1st); Indiana (1st); West Virginia (1st); Kentucky (1st or 2nd), Oregon (1st); California (2nd), Montana (1st), New Jersey (2nd), New Mexico (2nd), North Dakota (1st), South Dakota (2nd)

Jim Webb

Status: Dropped out. Webb announced on October 20 that he would withdraw from the Democratic race. He considered an independent run for president instead, but ultimately decided against it. Webb never received more than 6 percent support in a national, Iowa or New Hampshire poll.

This article was originally published on April 28, 2015 and has been updated regularly.