It's a combination of a lot of different things, though. It's not just immigration is what I'm saying. The problems the party has also include an economic outlook among the majority of hispanics that is different from the party's.
I think the problem is latinos think republicans don't like them. Its not the immigration issue, its how fierce the right fights to be the toughest on immigration. And I think Hispanics perceive them to be racist.
Would you vote for someone you thought didn't like you b.c of something you don't control? I don't think you would.
I personally think the republican argument of pro-liberty, smaller gov't appeals to a large segment of the population. But they frick it up with their stance on other issues: gay marriage, abortion, immigration, etc. If they could just shut the frick up, then they might do better with certain demographics including hispanics.
But the thing is they won't STFU. They are going to keep babbling about legitimate rape, two border fences, self deportation, etc. Then they are going to get all angry about how this country is ruined, and imply its minorities that are ruining it.