I agree with your very clear analysis Sandy. You can't both split your core constituency and fail to pick up other voters and win with any consistency. Particularly if the Republicans want to start winning they have to attract the Hispanic/Latino vote or they'll never catch up. There isn't a day goes by hardly that I do not hear Spanish spoken as I'm out in public. I sure wish I'd taken Spanish in High School.
The stand the Republicans keep taking on immigration is part of what is hurting them. We have a very conservative Congressman Steve King in NW Iowa. He is very anti-immigration reform. He is very popular among the conservative base in the area. But as I watch the Latino community grow, I just can't imagine it won't catch up with him some day.