To the moronic OP: The federal government isn't allowed to deal with criminal law. Criminal law - including rape - is left to the states. So voting for this bill is simply supporting the Constitution and the rule of law.
The Constitution mentions several federal crimes, and the Crimes Act of 1790 (adopted by the First Congress) lists 17 more. The federal government has been authorized to involve itself in criminal law from the very beginning.
Now, the federal government has a massive and ever-increasing role in criminal law. Ever heard of the Justice Department?
Whether this is good or not is a separate discussion; the point here is that you can't allow that libertarian bubble you're in to distort your vision of reality!