There are a lot of US states that have skirted union protections by not banning unions themselves, but just banning workplaces from requiring union membership for employees. It's called a "right to work" law that is implemented many different ways in many different states that makes unions a hard thing to nail down for the federal government.
As far as a federal ban on these laws, I think we are more in a position of fighting against a federal version of them, which is more likely to have support, than we are in a position to fight for a federal ban against those laws, though there are efforts.