Since Prop 187 was approved by the people themselves, I'm going to hazard a guess that that's not what was responsible for the Republicans' loss in California. As for its effect on Hispanic support for the Republicans, according to Rich Lowry, anyway:
"Republicans were getting about 30 percent of the Hispanic vote before Proposition 187, and have been getting about 30 percent since. Their basic political problem with Hispanics is that they are poor, and poor people vote for Democrats."
The RNC's heavy support for squishy moderates in California primaries couldn't possibly be the problem out here. No, it has to be the one-issue nativist xenophobe conservatives that are the problem. The fact that a lot of latinos are among the knuckle-draggers fed up with Open Borders is of no consequence. We MUST reward the Undocumented Workers in order to curry favor with... with... you know.... the lawbreaking element that we need in order to win elections. Yeah, that's the ticket.