1. On the one hand, perhaps over generalizing here, voting is determined by each state.
2. On the other hand there is a legal principal that the federal government cannot be held at ransom
by the state governments.
has always been apart of the conflict in our government. One part has been "liberal" vs "conservative".... the other has been (oversimplifying) "federal union" vs "state autonomy".
In the short term, if
the 18 states in question were to pass their legislation on the topic and apply them to the 2020 election... based on the time frames of legal proceedings and the Supreme Court... it is likely that they would stand for the 2020 election.
We would then... speaking hypothetically... if Trump were to lose, we would face numerous legal challenges to the election.
What would happen...?
Trump might refuse to give up office until the Supreme Court made its decision....
This might lead to a 2nd set of voting...
Congress, and maybe our military, would have to decide whether or not to accept the election results... OR
leave Trump in office pending a final decision.
Basically the USA would be thrust into a full blown Constitutional crisis.
Regardless of the Supreme Court's decisions, the Congress position and the military's position... (if Trump challenged the election results) the USA would be massively divided as to the outcome.
If the result was that Tump refused to leave office, and remained in office, there is a high likelihood of violence in the streets.
... which might also come if he were pushed out of office by the Supreme Court, Congress and supported by our Military.
Democracy in the USA would be challenged as never before... even beyond our Civil War, which only addressed states leaving, not over turning our Constitution.
Some people, some here on TFS, would be ecstatic... at first...
Then the USA, as we know it, would fall.