The linked website presents the current wording of the Article II, Section 1, of the U.S. Constitution; which states:
"Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress …"
To some people this clause means that the Governor of each state appoints the state's elector according to the existing rules proscribed by the state legislatures; while other people take this clause to mean that state legislature can appoint the electors. The correct interpretation of this clause could conceivably become a point of contention in states like Michigan and Pennsylvania where the governor is from one party and the state legislature is controlled by another party, if the electors are not certified by December 8, 2020.
Heading: "Signed in convention September 17, 1787. Ratified June 21, 1788. Portions of Article II, Section 1, were changed by the 12th Amendment and the 25th Amendment"
https://constitutioncenter.org/interactive-constitution/article/article-iiExtract: "Section 1
The executive Power shall be vested in a President of the United States of America.
He shall hold his Office during the Term of four Years, and, together with the Vice President, chosen for the same Term, be elected, as follows:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.
The Electors shall meet in their respective States, and vote by Ballot for two Persons, of whom one at least shall not be an Inhabitant of the same State with themselves. And they shall make a List of all the Persons voted for, and of the Number of Votes for each; which List they shall sign and certify, and transmit sealed to the Seat of the Government of the United States, directed to the President of the Senate. The President of the Senate shall, in the Presence of the Senate and House of Representatives, open all the Certificates, and the Votes shall then be counted. The Person having the greatest Number of Votes shall be the President, if such Number be a Majority of the whole Number of Electors appointed; and if there be more than one who have such Majority, and have an equal Number of Votes, then the House of Representatives shall immediately chuse by Ballot one of them for President; and if no Person have a Majority, then from the five highest on the List the said House shall in like Manner chuse the President. But in chusing the President, the Votes shall be taken by States, the Representation from each State having one Vote; A quorum for this Purpose shall consist of a Member or Members from two thirds of the States, and a Majority of all the States shall be necessary to a Choice. In every Case, after the Choice of the President, the Person having the greatest Number of Votes of the Electors shall be the Vice President. But if there should remain two or more who have equal Votes, the Senate shall chuse from them by Ballot the Vice President.
The Congress may determine the Time of chusing the Electors, and the Day on which they shall give their Votes; which Day shall be the same throughout the United States.
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.
In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President, and the Congress may by Law provide for the Case of Removal, Death, Resignation or Inability, both of the President and Vice President, declaring what Officer shall then act as President, and such Officer shall act accordingly, until the Disability be removed, or a President shall be elected.
The President shall, at stated Times, receive for his Services, a Compensation, which shall neither be increased nor diminished during the Period for which he shall have been elected, and he shall not receive within that Period any other Emolument from the United States, or any of them.
Before he enter on the Execution of his Office, he shall take the following Oath or Affirmation:--"I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."
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The linked 'MarketPlace' article believe that state governors get to choose electors if the electors are not certified by December 8, 2020.
Title: "How the election certification process works, and why it matters"
https://www.marketplace.org/2020/11/13/how-election-certification-works-when-will-2020-be-certified/Extract: "Trump’s campaign has filed lawsuits in Michigan, Pennsylvania and Arizona, calling for judges to stop states from certifying election results with claims of election fraud and limits placed on poll watchers. (To be clear, there is no evidence of widespread election fraud. A joint statement released Thursday from federal agencies states the Nov. 3 election “was the most secure in American history.”) If states don’t certify their election results by the deadline, it then falls to the state — usually the executive of that state — to choose electors. The thinking is that those states would choose electors sympathetic to Trump, said Casey Burgat, director of the Legislative Affairs program at the Graduate School of Political Management at George Washington University.
…
“I can’t imagine that across each of those three states, it would be done to that magnitude,” Burgat said. “You’d have to get all of them to make it worthwhile, and that [would be] a lot of votes and a lot of ballots just basically being thrown out.”"