*Clarification appended

On immigration policy, there are no major differences between the Republican candidates running for lieutenant governor in Texas.

But since the campaigning began in August, the issue of immigration has consumed countless minutes of television airtime and has taken center stage at the more than two dozen forums at which the four men have appeared together.

The talk has become heated, in particular from state Sen. Dan Patrick, the Houston Republican who is among three challengers trying to unseat the incumbent, David Dewhurst.

Patrick’s description of the influx of undocumented immigrants from Mexico to Texas as an “illegal invasion” drew the ire of Mayor Julián Castro of San Antonio, a Democrat, who called Patrick the “most anti-immigrant Republican running for office.”

Patrick responded by inviting Castro to debate. But he did not stop using the term, which he repeated during the race’s first statewide televised debate with a call to “stop the invasion” across the state’s southern border.

Members of Patrick’s own party have criticized him for his remarks, which pose a particular challenge for Republican groups trying to court Hispanic voters.

“I understand the need to address the issue of illegal immigration, and I understand the need to secure borders, and I realize that’s critically important,” said Hector De Leon, a chairman of the Associated Republicans of Texas. “But by the same token, that issue can be addressed by not engaging in rhetoric that sounds like thinly veiled racism.”

While each candidate in the Republican primary for lieutenant governor opposes amnesty for undocumented immigrants, supports a guest worker program, and favors heightened security on the border, their tenor in discussing the topics has differed.

Patrick has focused on the crimes committed by undocumented immigrants once they cross the border into Texas — even when asked specifically about the policies he would support to address immigrants without a criminal background, as he was during the recent debate. Besides Dewhurst, the other candidates are Jerry Patterson, the land commissioner, and Todd Staples, the agriculture commissioner.

“Until you secure the border, you really can’t address those other issues,” Patrick said, citing statistics about rapes and murders committed by undocumented immigrants in Texas.

In response to the same question, Dewhurst said that during his tenure he had worked to “shut down the border from the Gulf of Mexico to Laredo,” increasing the number of high-altitude spotter aircraft and armored vehicles that patrol it. Staples said that as agriculture commissioner, he has worked with landowners along the border, spending money he saved from his agency budget on “apprehending individuals, confiscating drugs” and conducting a “strategic military assessment” of illegal crossings.

While Patterson shared his opponents’ positions, he said he was frustrated that the debate had not focused on concrete solutions.

He said in an interview that Republicans would risk alienating Hispanic voters if they continued to rail against illegal immigration without presenting specific policy plans.

“When all you are doing is slamming immigrants whether they are legal or illegal, who primarily are Hispanic, then they only hear part of the story. They don’t hear that the Republican Party is not going to deport Grandma,” Patterson said. “They just hear that you are slamming immigrants, and they just hear that in the large sense, not just the illegals, but those who are here legally.”

In an interview, Patrick said Mexican-Americans shared his concern about the “significant issue” of criminals crossing the border into Texas.

“I am absolutely not, nor is any other conservative Republican, anti-immigrant,” he said. “We are anti-illegal immigrant, and we are particularly concerned about the hardened criminals who are crossing our border, and potential terrorists.”

Patrick said he was not concerned that his views might threaten the Republican Party’s long-term viability in the state.

“If somebody wants to disagree, that’s their right to disagree,” he said.

Less than a third of eligible voters in Texas are Hispanic, and the electoral impact of their increasing population is not expected to manifest itself in the current election cycle, said Jim Henson, a Texas Tribune pollster and director of the Texas Politics Project at the University of Texas at Austin.

This gives the Republican candidates room to move farther to the right in an effort to tap into the Tea Party electorate, voters who are more conservative on immigration than traditional Republicans and are driving the discussion within the party, Henson said.

Party strategists are “worried about the long-term prospects of the Republican Party if the immigration rhetoric remains as pitched as it is,” Henson said. “But you’re not seeing that translate into candidates’ positions very much.”

De Leon said he feared that Patrick’s remarks could alienate voters in a state where Hispanics are expected to make up a plurality of the population by 2020 and become an increasingly crucial voting bloc.

“I think it’s inappropriate to be shortsighted in terms of achieving political office now and not farsighted in terms of what is best for the Republican Party in the next 10 to 15 to 20 years,” De Leon said.

George Antuna, a founder of Hispanic Republicans of Texas, agreed. He said Patrick’s remarks could have been more “comprehensive in nature” and undermined Republicans’ efforts to attract Hispanic voters.

“I understand that the senator is trying to be the end-all-be-all within the primary, but we have a very serious challenger in the general election, and I think Sen. Patrick is unfortunately not doing himself any favors in the primary,” Antuna said.

The winner of the Republican primary is expected to face state Sen. Leticia Van de Putte, D-San Antonio. Van de Putte, a Latina, called Patrick’s language inappropriate and said he is using “the politics of fear to motivate certain voters” despite Republicans’ efforts to attract Hispanic voters — an initiative she has publicly scoffed at.

Van de Putte said the Republican candidates’ anti-immigration remarks showed that they were repeating the mistakes of Republicans in other states who stirred criticism among Hispanics after supporting strict, sweeping immigration policies.

“They’re not learning the lessons of Pete Wilson’s California,” she said. “They’re not learning the lessons of Jan Brewer’s Arizona.”

*Editor's Note: A statement in this story attributed to Texas Politics Project director Jim Henson has been updated to clarify his comments that the electoral impact of the increasing Hispanic population would not be felt during this election cycle.