Yes, but these apply to the registration and voting process itself. As far as I know there is no law regulating what a network can report as poll results (no matter how inaccurate) or those with whom they choose to collude. The risk is not one of legal consequences so much as breach of public trust. If major networks want to take that risk, that's their prerogative. Obviously folks these days are less inclined to buy their rubbish.
This may be true. In fact, as far as I know, it is. But it's time to start looking for the two-by-four to hit some of these people with.
Networks have to serve the public good as part of their license to use public airwaves. When the collude, it can be argued that they are no longer serving "the public" good, because they are serving another master.