CIS not a credible source??? Better tell that to your Republican congress. They testify for hearings all the time.
I'm sure that Congress will consider their testimony. Even the dems get to pick some that they will hear from.
I've read several of their studies and they are doing a better job with this issue then almost anybody. There work is very well documented with their sources referenced and verifiable. Here is an excellent example: The High Cost of Cheap Labor. Their work is far more believable then the nonsense that flows out of the National Chamber of Commerce where they just pluck a number out of their butt and expect us all to believe their self-serving assertions that we are going to be short by 10 million laborers by 2020 without documenting their methodology or their assumptions.