Unlike previous presidential elections, we most likely won’t know the winner of the 2020 race on election night, because more people will vote by mail due to Coronavirus restrictions. Mail-in ballots take longer time to process and may be more inviting for litigation and disputes, especially in swing states.
Some key states, like Florida, begin counting mail-in ballots before November 3, and many of these votes will already be tabulated by election night. In other key states, like Pennsylvania and Wisconsin, mail-in ballots are counted in Election Day and thereafter. Michigan can only start pre processing mail-in ballots 10 hours before Election Day.
If initial elections results are to be showing a tight race, like In 1876, the country may face a constitutional crisis. In that year multiple states have sent competing slates of electors to Congress. Louisiana, Florida and South Carolina sent competing sets of Electoral College votes to Congress, each with one set pledged to Republican Rutherford B. Hayes, and the other to Democrat Samuel Tilden. in Oregon, the Democratic governor replaced a Republican elector with a Democrat (alleging he was ineligible), thus throwing Hayes’ victory in that state into question as well. The Republicans refused to accept defeat by accusing Democratic supporters of intimidating and bribing African-American voters to prevent them from voting in those three southern states.
After long deliberations the Congress reached a compromise approving Hayes in return of ending the reconstruction process by withdrawal of federal troops from the defeated South. The premature withdrawal resulted in enabling a century of Jim Crow laws as requested by Southern Democrats.
The Constitution provides a vague guidance in a situation where Congress is faced with competing slates of electors from a single state or a thigh.
Even after passing the Electoral Count Act and the Compormise of 1877 which was intended to create a process for settling disputes like the one in 1876 over competing slates of electors, the language is untested and open to interpretation and dispute.
Although the odds of that happening are remote, well under 1%, it is not unheard of. In fact, three elections in the first 50 years of the republic were ties — in 1800, 1824 and 1836. And when you go to an interactive electoral map like the ones here at RealClearPolitics or at 270toWin.com, it’s not at all difficult to come up with plausible scenarios where neither candidate reaches a majority in the Electoral College — and instead they are deadlocked at 269-269.https://www.realclearpolitics.com/
Even if one party surpasses the count of 270 electors, unfaithful electors can theoretically switch and make the numbers even at 268 each or overturn results. Legislation allows states to overturn unfaithful electors but if a state doesn’t challenge those electors and the dispute can move on to congress and the SCOTUS. Currently there are 33 states that their legislature can force an unfaithful elector to be faithful, but the question remains if partisan governors would use their legislature to force it.