Donald Trump said at the Republican presidential debate Wednesday night his biggest weakness is that he trusts people too much.

"I'm too trusting and when they let me down, if they let me down I never forgive," he said in answer to the first question at the debate, hosted by CNBC.

Wednesday marked the third Republican primary debate.

The latest Monmouth University poll — released Monday — showed Ben Carson leading the field in Iowa by double digits, while Donald Trump held tight in second place.

Catch up with our live debate coverage here or watch it live here.