I recommend Elizabeth Llorente's analysis at Fox News Latino on the Latino vote, which explains the current situation well. One interesting point is that immigration is not just a policy issue, but also has a strong personal element. So you might rank immigration low on your list of priorities, but you are rubbed the wrong way when Rick Santorum says that breaking up families is "worth it" because "this is just who we are."
Even the Republican Party seems to accept this premise. Despite the fact that its two viable presidential candidates very vocally oppose immigration reform and applaud more enforcement and deportation, the party itself tries not to mention it.
“Once again, Latino voters reaffirm their belief that the most important issues are the economy and jobs,” said RNC spokesperson Alexandra Franceschi. “President Obama’s broken promises and failed policies have only brought record debt, out-of-control spending, and higher unemployment to the United States, all of which have disproportionately hurt Latinos struggling to make ends meet in this difficult economy. “
That isn't a winning strategy if Latinos are turned away from an economic message they might like by the personalized rhetoric of immigration.