Ben Carson is known for his extraordinary work as a brain surgeon for children.

VOA: special.2009.09.04

Ben Carson soon became the top student in his class.

VOA: special.2009.09.04

His mother,Sonya Carson, raised Ben and his older brother on her own.

VOA: special.2009.09.04

Neurosurgeon Ben Carson interestingly appears on the poll -- the only one on the list who's never been elected to public office.

CNN: Possible 2016 candidates make CPAC pilgrimage

But as the front-runner trying to hold on to the lead as retired neurosurgeon Ben Carson's numbers grow, it's difficult to see how Trump wasn't at least partially wounded by Thursday's performance.

CNN: 's Republican debate: Winners and losers - CNNPolitics.com

There had always been hope in the Walker campaign that Trump supporters were not active caucus-goers, the source said, but it was hard to fight the popularity of both front-runner Trump and Ben Carson.

CNN: Scott Walker drops out of 2016 race - CNNPolitics.com