No question that there is some intimidation that is taking place. If you saw the thread on Hayworth's remarks, you can see how arrogant some pro-immigration groups are concerning this.
I think public opinion will eventually have an effect, but due to the factors you mention it will take several years. If you look at similar social issues like crime or welfare, it took many years from the time a public consensus formed until we took some action--building more prisons, starting to cut back on welfare and so forth. (Not to say I'm totally happy in those areas, either, but eventually we did do something.)