Hispanics are by definition a mixed race. I seriously doubt that most Texans would consider Mexicans as being white. In fact, Trump particularly pointed out that the Mexicans coming into the USA were criminals. He didn't say that about other white countries like the UK, France, etc.

In Samuel Huntington's "Who are we", he states that Hispanic immigration to the US is very different, because they are living contiguous to the ancestral homes. They also have a claim on states like Texas, California, Florida that were ruled by the Mexicans or Spanish not that long ago.