In 2008, Hispanics, according to the latest figures, were 7.4 percent of the total vote. White folks were 74 percent, 10 times as large. Adding just 1 percent to the white vote is thus the same as adding 10 percent to the candidate's Hispanic vote.
If John McCain, instead of getting 55 percent of the white vote, got the 58 percent George W. Bush got in 2004, that would have had the same impact as lifting his share of the Hispanic vote from 32 percent to 62 percent.
But even Ronald Reagan never got over 44 percent of the Hispanic vote. Yet, he and Richard Nixon both got around 65 percent of the white vote.
All I can say is, if you want to know why Iraq and Nigeria will never be a functional democracies, look no further than Mr. Buchanan's observations. As Matthew Yglesias points out, identity politics along racial, ethnic, or religious lines becomes much more effective as a country becomes more diverse:
At any rate, while Buchanan is being repugnant, I do think this is something conservatives are going to want to think about. Consider the case of Jeff Sessions (R-AL). We’re talking about a guy who’s too racist to get confirmed as a judge, but just racist enough to win a Senate seat in Alabama. And it’s not because Alabama is a lilly white state. With 65 percent of its electorate white, and 29 percent of its electorate African-American, Alabama is much more demographically favorable to the Democrats than is the country at large. But while McCain pulled 55 percent of the white vote nationwide he scored 88 percent of white vote in Alabama. And this is what you tend to see in the Deep South, white Americans exhibiting the kind of high levels of racial solidarity in voting behavior that you normally associate with African-Americans in the US political context. ...
An analogy might be to religion. When the country was overwhelmingly Christian, Christianity didn’t play much of a role in our politics. But as the Christian majority shrank it became more and more viable to explicitly mobilize Christian identity for political purposes.
The difference between me and Yglesias is that he's outraged by this sort of demagoguery and census-style bloc voting, whereas I see it as the natural human condition. Loathsome, but as inevitable as the sunrise.