Texas Gov. Rick Perry speaks about border security during a news conference Thursday, Sept. 10, 2009 in Houston. (AP Photo/David J. Phillip) (David J. Phillip/AP)

Texas Gov. Rick Perry’s support for a law allowing illegal immigrants in Texas to pay in-state tuition is emerging as a key vulnerability as he seeks to maintain his frontrunner status in the Republican presidential race.

At Thursday’s GOP debate in Florida, Perry defended his support for the Texas DREAM Act by calling critics of the law insensitive. “If you say that we should not educate children who have come into our state for no other reason than they have been brought there by no fault of their own, I don’t think you have a heart,” Perry said.

The comment drew immediate criticism from his rivals, who have called the Texas law a “magnet” for illegal border-crossers, a taxpayer subsidy for lawbreakers and evidence that Perry is not the unwavering conservative he appears to be.

“I think if you’re opposed to illegal immigration, it doesn’t mean you don’t have a heart, it means you have a heart and a brain,” former Massachusetts governor Mitt Romney told conservative activists Friday morning at the Florida conference of the Conservative Political Action Committee.

It is a line of attack likely to continue as Perry struggles to defend his record on immigration, an issue that has grown more emotional since he signed the Texas DREAM Act in 2001. Many conservatives have favored a no-tolerance attitude toward illegal immigrants in recent years, calling them a threat to public safety and a drain on public resources.

Perry, however, has maintained his support for a program that has given tuition breaks to more than 32,000 students attending Texas colleges. The law sparked a national movement to pass a federal version, which has been championed by President Obama and became a bitterly contested issue that failed in Congress last year.

Perry has said he opposes the federal version, calling it “amnesty” because it includes a path to citizenship. The Texas law does not have such a provision. Rather, its supporters said it was intended to reduce the barriers to higher education for children brought to the country illegally by their parents or other adults.

The measure applies to undocumented students who have graduated from a Texas high school, lived in the state for three years and signed an affidavit promising to seek legal status. They can become eligible for scholarships and pay in-state tuition rather than international student rates, which are sometimes double and triple the resident fees.

Perry has gotten some praise from his tea party backers for sticking to his guns on the issue. In the debate, Perry explained his view that educating illegal immigrant children prevents them from becoming a drag on society and noted that the DREAM Act passed with bipartisan support.

But he has also taken heat for his opposition to a fence that would stretch the length of the U.S.-Mexico border, which his foes say is further evidence that Perry is soft on one of the Republican Party’s litmus test issues this year.

He tried to reaffirm his conservative credentials on the issue of illegal immigration by noting that his state invested $400 million into border security. He said he sided with Arizona on the state’s controversial law aimed at deporting more illegal immigrants, though in the past he has said that approach is not right for Texas.

In Texas, where border policy and other immigration issues often dominate the news, the DREAM Act has drawn surprisingly little notice.

It was the first of its kind when it passed a decade ago — now about a dozen states have such laws, and one is under consideration in Maryland — and it drew overwhelming support from both parties in the Texas legislature.

Repeated attempts to repeal it have failed, including one this year. Even some members of the state’s vast tea party network say that they have no problem with it.

“We in Texas have a very long record of being neighbors to Mexico,” said Clint Cook, a spokesman for the Texas Tea Party Alliance. “Yeah, you could say that some taxpayer dollars are being used, but at the same time those kids graduate from college and go on to create money for the economy.”

Last year, Texas education officials estimate that illegal immigrant college students received about $9.5 million in state financial aid. And the Texas Higher Education Coordinating Board said that last year more than 16,000 students were in the program — an uptick from previous years but still a small fraction of the more than 1.3 million students attending state colleges and universities.

Critics of the law say they have grown increasingly frustrated as the economy has deteriorated and more illegal immigrants sign up for discounted tuition. They say it takes seats away from qualified legal students and that taxpayers should not be forced to subsidize the education of those in the country illegally.

Maria Martinez, executive director of the Immigration Reform Coalition of Texas, a nonprofit that advocates for stricter immigration enforcement and opposes the Texas DREAM Act, speculated that Republicans who take a soft tack on these issues are likely doing so under a misguided attempt at winning Latino votes.

“Politicians tend to try to be all things to all people, and Perry probably thinks if you have a big tent rather than stand on your principles, that will get you elected,” said Martinez. But at a time of high unemployment and dwindling resources, “you just can’t tell me you’ll win any popularity contests as a politician having that position.”

The bill was introduced by Rick Noriega, a former Democratic state representative from the Houston area, who was inspired to act after meeting an ambitious young high school graduate from El Salvador. The graduate was cutting lawns rather than attending college because he had lived in the state illegally since age 14.

Today, the student is a U.S. citizen and “he’s working as an aviation mechanic for Continental Airlines, has a house, is looking for a wife and complains that his taxes are too high,” Noriega said. “If that isn’t American, I don’t know what is.”

In the decade since the law as passed, the landscape on immigration has changed with the Sept. 11, 2001, terror attacks, an increase in drug-related crime across the border and rising opposition to illegal immigrants. Backers of the state policy acknowledge that the law would be much less assured of passage in the Republican-dominated Texas legislature today.

And Perry’s tone on some immigration issues has shifted. Early in his governorship, he advocated for more unfettered transportation across the U.S.-Mexico line and health services that could span both sides of the border.

This year, however, he backed a bill requiring a bill barring “sanctuary cities” — communities that adopt policies declining to share information with federal immigration authorities. He approved strict new rules requiring voters to show proof of identification before casting their ballots and made significant cuts to public education. Both were criticized as disproportionately affecting minorities.