Dr. Ben Carson is the former head of pediatric neurosurgery at Johns Hopkins University in Baltimore, Maryland. The retired doctor is an expert at surgically separating babies who are born joined together.

Dr. Carson has a strong personal story. He grew up in poverty and rose to be a top children’s neurosurgeon. He became well known among political conservatives for his criticism of President Obama and the “Obamacare” national health care plan.

He has never run for political office before, a fact that appeals to some voters. He wants major tax reform and to end Obamacare. Some of his statements, such as comparing ISIS to the U.S. Founding Fathers, have drawn criticism.

He announced his candidacy on May 4, 2015.