Rick Perry went on the defense on the topic of immigration during the Republican debate Thursday night, but stood behind his support for a bill that provided in-state tuition to some undocumented students.

"If you say that we should not educate children who have come into our state for no reason than they've been brought there, by no fault of their own, I don't think you have a heart," he said. "I still support it greatly."

The other candidates piled on Perry, criticizing him for his support for the in-state tuition bill. The bill allows some undocumented students, who went to high school in Texas and are working toward legal status, to qualify for in-state tuition at Texas state colleges.

"You're sort of making this leap that unless the taxpayers subsidize it they won't be able to go," Rick Santorum said. "The point is, why are we subsidizing this? Why should they be given preferential treatment as an illegal in this country?"

"Yes, I would say that he is soft on illegal immigration," he added.

Perry's statements on the border fence were also a point of contention. While the others said the border must be secured with a fence, Perry argued a fence would not work as well as boots on the ground.

The most substantive question was about E-Verify, an employment verification program already used by federal agencies and contractors to screen for undocumented workers. Newt Gingrich said he would support making the program nationwide, as some House Republicans hope to do, and dismissed worries that it would cost employers.

"We'd be far better off to outsource E-Verify to American Express and Mastercard and Visa because they actually know how to run a program like that without massive fraud," Gingrich said. "Second, the program should be as easy as swiping your card to buy gasoline, so I would ask of employers, what is it you would object to?"