I can't take Rand Paul seriously when he utters stupid statements like that (and he is far from the only one pushing that meme). Being an American is about FAR more than simply "living and working" here. Back when we used to actually enforce our immigration laws, we were very selective about who we allowed in and to whom we bestowed the privilege of citizenship. When wise people actually ran things, they tried to ensure that anyone permitted to immigrate would be an asset, rather than a detriment, to our society. They also took the common sense measure of quarantining prospective immigrants to ensure that they did not import diseases. And those seeking citizenship were required to renounce any allegiance to any other country, become proficient in English, and embrace the principles upon which the U.S. is founded.
Now, however, we truly have anarchy. "Immigrants" get to decide for themselves when and how to come here and we are expected to just accept it. Any suggestion that they should desegregate themselves once here and embrace American culture is met with shouts of "racist!" and "xenophobe!" The resulting epidemic of crime and third world disease is covered up by the media and ignored by politicians. And these same politicians have become so corrupted by the lure of obedient votes or cheap labor that they simply no longer care about adhering to their sworn oaths, nor do they really care about America's founding principles. And sadly, I'm talking about politicians on "our side" here....the Democrats are simply the worse side of the same coin.
America cannot continue to be America without Americans. To be American requires a common civic character and allegiance to a common set of guiding principles. If immigrants want to come here from wherever, renounce the governing principles of their home country, and fully embrace American culture and philosophy then great, get in line and follow the process. Prove that you are American material. If however, they simply want to come here "to live and work", but continue the same beliefs and behaviors of their home country culture, then we would be idiots to accept them.
I take him seriously, as the demagogue and Democrat-in-all—but-name that he is.