Good luck finding a site that can host an event of this complexity on such short notice in the context of a global pandemic and societal unrest.
Trump doesn't have the power to do that, it rests solely with Congress. More interestingly, there's the entirely seperate clause in the 20th amendment to your constitution: "The terms of the President and the Vice President shall end at noon on the 20th day of January.”
So the only thing being delayed is the inevitable.
1) There are lots of sites in northern and central FL who will be more than happy to accommodate the president. Northern FL will not impose any pandemic conditions, and will allow large crowded rooms.
2) In my personal opinion, Trump has taken many actions that contradict US law, US precedents and the Constitution. Why stop now? Any delay of the elections will be litigated, and eventually be decided by the Supreme Court. This president just yesterday indicated that he would personally send in the US military to police the cities (even if the governors say no), if the governors continued to do a poor job. Will the Supreme Court prevent them from doing this? Perhaps, perhaps not. Trump has threatened to cut off federal aid from states who have to much of their election based on mail-in ballots. Will the Supreme Court stop him? Trump has threatened to stop aid to states that allow sanctuary cities. There is a very. very long liftoff such actions. And be clear, his 40% strongly support his actions.
You seem to assume that Trump will obey the law. His AG says that he cannot commit any crimes while in office. I suspect that delaying an election during the second wave of the worst medical emergency since WWI will qualify for a reason to delay the election, and that even the Supreme Court might agree.
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And just BTW, if there is a 2nd wave in the Fall, many Americans will support a delay. Will we really take to the streets to demand that we have a mail in election? Some states have accepted this, some not.
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AND JUST BY THE WAY
What do you think will happen when Trump is "declared" the loser after the last counting of the mail-in ballots. How many court cases do you think will be started in how many states and counties? Trump, as he did last time, will declare that there has been rampant fraud and that he is the winner, no matter the result.
This country is a very long way from having president other than Trump.