As a Native Texan, I am paying attention to this one from Florida. I watched the debate on live streaming and Ted came away from that one the decisive winner in content and delivery. I would think the debate was the biggest reason for his surge.
I watched that debate with a number of folks I had not previously known and immediately polled them afterwards. Not one of them thought Dewhurst won the debate and the VAST majority, some of which had been Dewhurst supporters previously, said that they were now definitely going to vote for Ted Cruz.