Hillary Rodham Clinton
The former first lady and Democrat has built the largest campaign operation of any potential candidates thus far with headquarters in Brooklyn.
Donald Trump
The prominent business mogul's decision to run for the Republican party's presidential nomination has raised quite a few eyebrows.
Bernie Sanders
The 73-year-old from Vermont said in his campaign announcement that, "After a year of travel, discussion and dialogue, I have decided to be a candidate for the Democratic nomination for president."
Ted Cruz
Elected in 2012, this Republican was the first Hispanic or Cuban American to serve as a U.S. Senator from Texas.
John Kasich
The Ohio governor presents himself as a more traditional, moderate Republican in the field crowded with far-right conservatives.
Marco Rubio
UPDATE: Rubio suspended his campaign on March 15 after losing his home state's primary to Trump.
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The Florida senator has marketed himself as a "forward-thinking" leader within the Republican party.
Ben Carson
UPDATE: Not long after announcing that he didn't see a way forward for his campaign, he pulled out of the race on March 4.
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This Republican nominee hopeful was the first surgeoun to succesfully separate conjoined twins at the head.
Jeb Bush
UPDATE: After finishing fourth in the South Carolina primary, the GOP candidate dropped out of the race.
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If the former Florida governer wins the 2016 presidential election, he would be the third Bush to run the United States.
Carly Fiorina
UPDATE: Fiorina suspended her campaign a day after a poor showing in the New Hampshire primary.
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Previously named the most powerful woman in American business, the Republican said in her campaign announcement, "I think I'm the best person for the job because I understand how the economy actually works."
Chris Christie
UPDATE: He suspended his campaign after coming in sixth in the New Hampshire primary.
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The New Jersey governor is looking to put Bridgegate behind him and announced his candidacy from his former high school.
Rand Paul
UPDATE: The Kentucky senator suspended his campaign on Feb. 2, a day after finishing a distant fifth in the Iowa caucus.
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The Republican senator wrote on his website that he hopes to, "return our country to the principles of liberty and limited government."
Mike Huckabee
UPDATE: After finishing ninth in Iowa, the 2008 caucus winner suspended his campaign.
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The 59-year-old was previously a candidate in the 2008 Republican presidential primaries.
Rick Santorum
UPDATE: The former senator suspended his campaign after the Iowa caucus and endorsed Sen. Marco Rubio.
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This Republican slammed the Supreme Court's recent legalization of gay marriage, calling the next president to fight it "for the survival of our country."
Martin O'Malley
UPDATE: After a disappointing showing in the Feb. 1 Iowa caucus, O'Malley suspended his campaign.
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"We must save our country now. And we will do that by rebuilding the dream," the Democrat said in his campaign announcement.
George Pataki
UPDATE: The moderate Republican announced he was suspending his campaign on Dec. 29, 2015. "I'm confident we can elect the right person. Someone who will bring us together and who understands that politicians—including the president—must be the people's servant and not their master," he said.
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The 70-year-old Republican served as the governor of New York from 1995 until 2006.
Lindsey Graham
UPDATE: Graham suspended his campaign on Dec. 21.
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The Republican has served as a United States Senator from South Carolina since 2003.
Bobby Jindal
UPDATE: The Louisiana governor dropped out of the race on Nov. 17.
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The Republican candidate has roots in Baton Rouge, La., with immigrant Indian parents.
Lawrence Lessig
UPDATE: Lessig suspended his campaign Nov. 2, saying in a video statement that the Democratic party had "changed its rules" regarding debate inclusion.
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The Harvard Law Professor met his self-imposed goal of crowd-funding $1 million by Labor Day. As a result, he announced on ABC that he's officially running for the Democratic nomination for President.
Lincoln Chafee
UPDATE: Chafee pulled out of the race on Oct. 23 after his bid failed to gain traction—or much money.
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A former Republican senator and Rhode Island governor, Chafee cast the party's only vote against the Iraq war and is now running on the Democratic ticket.
Jim Webb
UPDATE: Webb withdrew from the race on Oct. 20, 2015, a week after the first Democratic primary debate. He has reportedly not ruled out running as an Independent.
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The former Democratic senator from Virginia and secretary of the Navy under Ronald Reagan announced his candidacy—the fifth Democrat to do so—in a lengthy blog post, writing that he will provide the "proven, experienced leadership that can be trusted to move us forward from a new President's first days in office."
Scott Walker
UPDATE: Walker dropped out of the race on Sept. 21.
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The Wisconsin governor is the 15th GOP candidate to seek the Republican nomiation. "America needs new fresh leadership with big bold ideas from outside of Washington to actually get things done," Walker said in his first campaign video.
Rick Perry
On Sept. 10, 2015, the former governor of Texas was the first GOP hopeful to drop out of the race.