Ted Cruz showed Thursday night at the GOP debate how to take on Donald Trump and how to handle the birther issue. Cruz did what the Club For Growth had done effectively in Iowa.  He merely quoted Donald Trump.

When Neil Cavuto asked Ted Cruz about his birth, Cruz quoted Trump from September. Back then, Trump said his lawyers had checked into it and it was a non-issue. 

Cruz pointed out the only thing that had changed was the poll numbers. 

Then Cruz planted a seed of doubt on Donald Trump. A lot of birthers say both parents have to be born in the United States for the child to be a natural born citizen. 

Cruz pointed out that under that definition, adopted by many Trump supporters, Rubio, Cruz, and Trump would be ineligible because Trump’s mother was born in Scotland.

It was a very strong play out of the gate by Ted Cruz. 

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Whenever the moderates pitted Cruz and Trump against each other, Cruz quoted Trump’s own words. 

Trump managed to make a mistake by admitting that the only reason he was using the birther issue was because of Cruz’s polling.

That just reinforced Cruz’s point that it was an opportunistic attack Trump really did not believe.

Cruz, Trump, and Rubio had strong performances in South Carolina.  Out of the gate, with the birther issue, Cruz knew it was coming and hit it out of the park. 

Trump did manage to get the better of Cruz in the exchange on New York and Rubio got the better of Cruz on Cruz's record and taxes.

Overall, the other candidates were just stage warmers for the real fight between Cruz, Trump and Rubio. 

The only question left, and one I cannot answer, is whether anyone changed their mind.

Erick Erickson is a Fox News contributor. He is host of "Erick on the Radio" and founder/editor of The Resurgent. He is the founder of RedState.com. Follow him on Twitter @EWErickson.