One federal court decision may answer the question of whether the outcome of an election can be changed if there was criminal activity. In Marks v. Stinson the outcome was to reverse a federal judge’s election. However, the Supreme Court refused to take up the appellate court’s decision.
The Third Circuit upheld a federal judge’s decision to strike down a 1993 state senate election involving fraud. The federal district judge ordered that the winner leave office and installed his opponent. In that case, several officials knew of the wrongdoing but did nothing.
In the 2016 presidential election, Republican Senate Majority Leader Mitch McConnell knew about the CIA’s conclusion that Russians interfered in the presidential election, but he did nothing.