Two entirely different sides of the coin. State’s authority to determine how the electors are chosen and the date that the authorized electors formally vote in the College.
Two things were driving the Bush vs Gore recount in 1999 Florida recounts. One was the procedural aspect whereby Bush wanted whole state recount vs Gore’s push for cherry picked Democrat heavy counties. The second though was to conclude the process by the Electoral College deadline so as to have Florida’s Electoral votes counted at that step. Miss the deadline, not counted, Miss the deadline, not counted is the situation that is setup to happen with the mass absentee balloting this cycle, IMHO. That and fraudulently tilting some states from red to blue for not only the President but also Congress and state level offices.
This would only happen if Congress passed a law that the President signs.
Elections are a state-by-state affair; there is no national election. There is only a uniform date for separate state voting. Beyond that, Democrats have sought to nationalize elections by dictating the process that all states must use.
Unless and until that happens, this mailed-out voting chaos would only affect the blue states that choose to do it. It will only hurt those blue states, since the red states will vote normally and get their tallies in on time.
-PJ