The four candidates are billionaire real estate magnet Donald Trump; two first term Senators Ted Cruz from Texas and Marco Rubio from Florida and the Ohio Governor John Kasich.

Days after his disappointing performance during Super Tuesday, Carson told the Conservative Political Action Conference that he is leaving the campaign trail.

"Even though I might be leaving the campaign trail, you know there’s a lot of people who love me, they just won’t vote for me. But I will still continue to be heavily involved in trying to save our nation," the retired neurosurgeon said.

Carson said he will be working on a number of initiatives, including serving as honorary chair of My Faith Votes, a non-profit organization dedicated to mobilizing the 25 million Evangelicals who didn't vote in the last election.

The Republican presidential race at the beginning of this year had as many as 17 aspirants, which has now narrowed to just four.

The Democratic presidential race has already been reduced to two – between Hillary Clinton, the former Secretary of State, and the Vermont Senator, Bernie Sanders.

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