Candidates can file lawsuits to challenge a state’s election result.
But, to be successful, they need to prove that the fraud really happened, and that it changed the vote count enough to change who won. So far, no lawsuits have been filed that include that kind of evidence.
Any of these cases must be settled by December 8 – which is the date that every state must submit its final results to congress.
The Electoral College meets on December 14. Congress formally counts the votes on January 6.
This formal count is the last opportunity to challenge a state’s results.
At least on Representative and at least on Senator can challenge a state’s results. For the challenge to hold, a majority of both the House of Representative and the Senate must vote in favor of overturning the state’s results. This is extremely unlikely in this election.
Once Congress accepts the Electoral College’s vote count, the election is complete.