I really don't think people mind immigration, you forgot the illegal part.
If you believe in a Constitutional form of Government as started by the founding fathers then mass illegal immigration is not compatible. In the beginning we needed immigrants, we were a developing nation, today we are developed and overpopulated, it's the same reason we are no longer are farming culture, or even mass industrial culture for that matter. Today the Chinese make a higher wage than the average Mexican, why is that?
The Constitution was formed here, not Mexico, Panama or Canada, mass immigration influxes have destroyed France, Great Britain, and other parts of Europe. Crime rates , poverty, violence et al have sky rocketed. Places like Australia, Japan, New Zealand all with very tough immigration policies have fairly low rates of poverty, violence and are in general more stable societies. Do they allow immigration, yes it's very slow and methodical.
All one has to do is look to California to see what mass immigration does, they are run by a single party are still going broke after the largest tax increase in history and businesses and the middle class are leaving in mass, mostly white flight.
The only ones left are extremely poor, and the super rich who need these poor people for gardeners, cooks and maids. Mass, uncontrollable immigration will always be bad.
You will soon have the Balkanization of the United States, if its not corrected which is what extremist groups like LaRaza truly want.
BTW - the whole work thing is a fallacy, there is a difference for working for nothing and wanting to work. There are millions of unemployed, college grads working for fast food, in addition only 9% of US crops are picked by migrants.