No. We have held elections during the Civil War and during World War I despite extreme conditions, so there isn’t any precedent for this. Some state and local elections have been delayed, however.

The Constitution divides the power over national elections between the states and the Congress and Article 2 of the Constitution does say that Congress could set a different election day if it so chooses.

If Congress postpones the election so that there is no one qualified to be president when the current president’s term expires, Congress does have authority to choose a president. So the power lies with Congress to choose the dates for a postponed election, or even to act itself if no election is held before next January.

Another issue is the Constitution makes no reference to any presidential authority to affect the timing or conduct of a national election. Joe Biden is understandably concerned that Donald Trump may seek to delay the election, but it is hard to find in the Constitution any basis for President Trump to do so.

You have to read very strong implied national emergency power into Article 2 to say the president has any authority at all.

On the other hand, the Constitution is very clear, both in Article 2 and in the 20th amendment, that Congress has the responsibility for choosing the time of election and for establishing what should be done if any election could not be held.

The way of conducting the election is left up to the states, and they could change to vote-by-mail methods if it looks like in-poll voting will not be practical. However, they should start preparing for this no later than mid-summer.