I believe that was July of 2010 in El Paso
Long before he decided to run for President.
Why has he backed down? See, I think when somebody runs for President they think they have to be likeable to the media. So they adjust their style or focus in order to match what they think is needed to get elected. That tells us who they are willing to answer to.
By now Perry has had a chance to realize that the media is going to attack him regardless of what he does to try to be liked. At this point he knows he needs to appeal directly to the people. I’m close enough to Iowa that I hear some of his ads, and they make good points. The one sticking point that got him in trouble with conservatives was the illegal immigration issue, and I don’t think he can get anywhere with conservatives until he addresses why he said some things and why somebody like Arpaio would endorse him.