There are still five candidates in the race for the Republican nomination for this year's presidential election. Here's a look at them:
Experience:Billionaire business mogul who is making his first foray into national politics. Built a real estate empire with large, profitable property developments in New York City.
Key policies: What does building a wall between the U.S. and Mexico do for you? He also grabbed headlines for his plans to put a ban on Muslims entering the United States while issues with immigration are sorted.
He also wants tax relief for middle class Americans and a simpler tax code, to reform the VA, and to show "strength" when discussing trade deals with China. A full list of his positions can be found here.
Fun fact: Appeared on WWE in 2007 in a challenge with fellow mogul Vince McMahon. They picked wrestlers to fight at WrestleMania, with the loser having to shave their head. Vince lost.
Campaign highlight: His defining moment might have come Friday when he won the endorsement of Chris Christie, who had been a huge anti-Trump critic before then.
Campaign misstep: He's arguably made many, not that it's affected his popularity, but he was accused by his rivals of cowardice when he refused to appear at a debate moderated by Fox News over tough questioning he previously received from host Megyn Kelly.
What his supporters say: "He is rewriting the playbook of American politics because he's providing strong leadership that is not dependent upon the status quo."
– New Jersey Governor and former Republican presidential candidate Chris Christie, as reported by the BBC
What his critics say:"I’ve got a ticket on the Titanic. So I am like on the team that bought a ticket on the Titanic, after we saw the movie. This is what happens if you nominate Trump."
– U.S. senator and former Republican candidate Lindsey Graham, reported by the Washington Post
Experience: Became an attorney after graduating from Harvard Law and became solicitor general of Texas in 2003. Served as an adviser in the 2000 presidential campaign of George W. Bush. He won election to the U.S. Senate in 2012
Key policies: Shrinking the size and power of federal government, eliminating the IRS as well as the departments of Education, Energy, Commerce, and Housing and Urban Development.
He also vows to "defend the Constitution," secure the border by ending "catch and release," increase deportations and stop sanctuary policies. You can read more of his policies here.
Fun fact: He was born in Calgary, Canada, to his Cuban father and American mother, and was a dual-citizen until he revoked his Canadian citizenship in 2014, according to MRCTV.
Campaign highlight: He won the first Republican Caucus in Iowa, a shock to some who thought it was Trump's to lose.
Campaign misstep: He said he'd abolish the Department of Commerce twice in this debate.
What his supporters say: "If conservatism is your bag, if conservatism is the dominating factor in how you vote, there is no other choice for you in this campaign than Ted Cruz. This is the closest in our lifetimes we have ever been to Ronald Reagan."
– Conservative talk show host Rush Limbaugh, as reported by Hot Air
What his critics say: "The man betokens such a level of ignorance and a direct falsification of the existing scientific data. "It’s shocking and I think that this man has rendered himself absolutely unfit to be running for office."
– California Governor Jerry Brown, on Cruz's views on climate change, as reported by MSNBC
Experience: The youngest candidate left in the race, Rubio is a first-term Senator from Florida who previously served as a Florida state legislator – becoming majority leader – as well as a West Miami city commissioner.
Key policies: He is calling for changes to the tax system that will help families (via a new $2,500 child tax credit) and small businesses (by cutting their taxes to 25 percent). He also is calling for full repeal of the Affordable Care Act.
He wants to end death taxes and repeal "burdensome" regulation on farmers. You can read more about his policies here.
Fun fact:Politico reports his wife, Jeanette Dousdebes-Rubio, is a former Miami Dolphins cheerleader who joined him when he attended his first ever rock concert – Prince.
Campaign highlight: Probably his best TV debate performance came on Thursday, CNN reports, when he went on the attack against Donald Trump and landed some blows.
Campaign misstep: It was in stark contrast to a debate performance earlier this month, when he was ridiculed by Chris Christie for repeating the same phrase over and over.
What his supporters say: "He worked for my '96 campaign in Dade County, Florida ... when he was a hard worker. He's young ... he wants to grow the party as opposed to Cruz. I don't know what he wants to grow."
– Former Republican presidential candidate Bob Dole, as reported by ABC News
What his critics say:"Donald Trump represents strength and Marco Rubio represents Washington D.C. We don’t need any more D.C. politicians!"
– Chris Christie, as reported by Breitbart
Background: He was elected as a U.S. representative for Ohio at just 30 years of age, after previously becoming the youngest state senator in Ohio history. He retired from Congress in 2000 and went into the private sector, before returning to politics in 2010 to become the Ohio governor.
Key policies: He has created "The Kasich Action Plan" he intends to implement in his first 100 days as president, reducing the size of government, cutting taxes for families and businesses, cutting federal regulations and balancing the budget within eight years.
He says the plan would "take back power from Washington." You can read his policies here.
Fun fact: After receiving a dorm citation as a freshman at Ohio State, Kasich appealed directly to the university president and convinced him to deliver his letter to President Richard Nixon, which ended up with Kasich meeting Nixon at the White House. Source: Newsmax.
What his supporters say:"In a campaign when most of the Republican hopefuls are as grim as a team of overworked morticians, Kasich remains positive and upbeat. Indeed, his tone has become an important part of his message: America needs an experienced, positive, optimistic, collegial problem-solver."
What his critics say:"Take a closer look at John Kasich, because while these other chumps make empty promises to do awful stuff, the so-called moderate gets awful stuff done."
– Comedian Samantha Bee, on Kasich's record on abortion and LGBT rights as Ohio governor, as reported by The Daily Beast
Background: Born in Detroit, he was the director of pediatric neurosurgery at the John Hopkins Children's Center in Baltimore for 29 years. Appointed to serve on President Bush's Council on Bioethics, he earned the Presidential Medal of Freedom in 2008.
Key policies: He's called for a 14.9 percent flat income tax on all Americans, irrespective of income, albeit by eliminating deductions on mortgage interest, charitable giving and state and local taxes.
He would also repeal and replace Obamacare with a new system of his own design. You can read more about his stances here.
Fun fact: He was played by Cuba Gooding Jr. in the made-for-TV movie: "Gifted Hands: The Ben Carson Story," CNN says.
What his supporters say:"As soon as I heard [Ben] Carson speak, I tried for three weeks to get on the phone with him. I was like this is the most brilliant guy."
– Kanye West, as reported by The Guardian
What his critics say:"Nobody has been able to sit down with him and have him get one iota of intelligent information about the Middle East."
– Duane Claridge, Carson's top advisor on national security, as reported by The Week.