A bare assertion isn't the same thing as the naked truth. You've made a counterfactual assertion. Prove me wrong.
http://pewresearch.org/pubs/1024/exit-poll-analysis-hispanics
This means that McCain won only 4% of the black vote, which is close enough to be called “monolithic”, because so many voted the same way, for Obama.
Hispanics, of which the vast majority in the US are Mexican, voted with one third of their support to McCain. Thus they are not a monolithic vote.
Importantly, this was *more* Republican than their mid-term election vote in 2006:
http://pewhispanic.org/files/factsheets/26.pdf
And previously, some 40% of Hispanic voters preferred W. Bush over Al Gore. Again, far more a monolithic vote.
So therefore, my assertion is quite factual.