Elements there may be, and even powerful ones within their denominational spheres - but the secular and antireligious journalistic establishment compares in influence with all of them put together. That is a very stable situation, IMHO - and therefore the disunity among the denominations precludes the establishment of any of them (or of Islam, if OBL is reading). Indeed, as I said, there is little doubt that the trend has been not toward established religion but toward established irreligion.If someone sneezes and the president says "God bless you!" the ACLU tries to make a court case of it. Recall the fatuous attempt to get the courts to enjoin the president not to refer to God in his second inaugural address. The court might have considered it, IMHO - if not for the fact that such an injunction could not possibly be enforced. The possibility of having a judgement flouted without consequence - very publicly and probably humorously - might tend to focus a jurist's mind . . .
Let's also not forget that early in our existance, there were communities that were largely one faith or the other and the institutions in those areas reflected that predominate faith. Jewish and Catholic come to mind, but I'm sure there were protestant situations also. And of course in Utah, prior to mass migration, if you weren't Mormon, you weren't anybody and had limited rights as the jobs, schools and courts had a decidedly Mormon bent. As I mentioned earlier, I remember back in the 80's when the Moonies tried to take over a region. I don't know what became of it.
America is soul searching now and it's not beyond the realm of possibility that there are those who could given the right tools and set of circumstances push forward a theocratic agenda. Frankly, even though he keeps getting soundly defeated, you would probably find such a person in Alan Keyes.