Under the Constitution, the presidential election (and therefore any fraud associated with it) is _both_ a state _and_ a federal issue.
(You can read Article 2 Section 1 and the Twelfth Amendment for the details.)
Congress (one vote per state) has the _final_ say.
https://www.facebook.com/shanevaughn38/videos/10219945275044223/
Which explains why trump will not concede and this will go right down to December 15th if need be.