They claim that skilled immigrants work for lower pay and take US jobs. But they can't be further from the truth. Skilled immigrants actually create jobs. And more than half of the engineering Ph.D. students in the US are immigrants. Immigrants have founded thousands of successful companies that employ millions of Americans.
Silicon Valley is dominated by immigrants.
There is hardly a major company in the Valley who's chief technical person isn't an immigrant. Yahoo, Netscape, HotMail, i3, Excite, and others are filled with extremely productive immigrant employees. Andy Grove, Intel's CEO and my personal pick for CEO of the decade, is an immigrant. I once took a survey of a 50-person industrial engineering class when I attended UC Berkeley. I asked the class how many people had at least one parent who was an immigrant.