The Electoral College system was established under Article II and Amendment 12 of the U.S. Constitution more than 200 years ago. What it means is that Americans vote for president indirectly. We see a candidate’s name on the November ballot, but we’re actually voting for a group of electors who will pick the winner in December. From Jamelle Bouie of The New York Times:

Under the Constitution, states can allocate electors — meaning electoral votes — in “such Manner as the Legislature thereof may direct.” Beginning after the Civil War, every state in the union has used direct popular election to choose electors. The modern process is straightforward. After the vote, election officials certify results and prepare “certificates of ascertainment” that establish credentials for each elector. There are multiple copies, and the governor signs each one. The electors meet, record their votes, and those votes and certificates . . . are sent to state and federal officials, including the vice president, who will preside when Congress counts electoral votes early next year. 

Under the theory of legislative supremacy over elections, however, . . . state legislatures could possibly circumvent governors and election officials to create different slates of electors to send to Congress, forcing a choice between the people’s electors and those of the legislature. If a state submits conflicting electoral votes, the House and Senate may choose which ones to accept or reject.

It has to be said that there is almost no chance of this happening . . .

[Note: I’d say there’s zero chance of it happening in enough states to change the result of the election. However: ] 

We are living through a period in which, for reasons of geographic polarization in particular, the Republican Party holds a powerful advantage in the Senate and the Electoral College, and a smaller one in the House of Representatives. Twice in 20 years they’ve won the White House without a majority of votes. A few shifts here and there, and Txxxx might have won a second term while losing by a popular vote margin nearly twice as large as the one he lost by in 2016.

The Republican Party, in other words, can win unified control of Washington without winning a majority of the vote or appealing to most Americans. Aware of this advantage, Republicans have embraced it. They’ve pinned their political hopes on our counter-majoritarian institutions, elevated minority government into a positive good (rather than a regrettable flaw of our system) and attacked the very idea that we should aspire to equality in representation. “Democracy isn’t the objective; liberty, peace, and prosperity are,” Senator Mike Lee of Utah tweeted last month. “We want the human condition to flourish. Rank democracy can thwart that.”

“Rank democracy.” Perhaps Lee, one of the leading intellectual lights of the Republican Party, is alone in his contempt for political equality between citizens. But I doubt it. And a Republican Party that holds that view is one that will do anything to win power, even if it breaks democracy. It’s a Republican Party that will suppress voters rather than persuade them, degrade an office rather than allow the opposition to wield it and create districts so slanted as to make it almost impossible for voters to remove them from office.

For that Republican Party, the Electoral College is a loaded gun, waiting to be fired. We’ll disarm and disassemble it as soon as possible, if we value this democracy of ours.

Unquote.

The good news is that there is an effort underway to practically eliminate the Electoral College. From NBC News:

[By approving Proposition 113 last week,] Colorado voters have decided to join a growing list of states that hope to decide a president by popular vote, the latest move in a national chess match over the way the United States elects its presidents.

Called the National Popular Vote Interstate Compact, the agreement calls for states to award their electoral votes to the winner of the national popular vote, once enough states join the agreement.

So far, 15 states and the District of Columbia have approved the pact, covering 196 electoral votes of the required 270 to win the presidency.

That 270 matters: The states that have approved legislation to join the compact agreed it would not take effect until the 270 threshold is reached. Once it does, those states will have the power to use their Electoral College votes to elect a winner, according to the popular vote. This uses the Electoral College to effectively phase out the Electoral College . . . 

Unquote.

These are the states that have enacted the Interstate Compact. Will enough voters, legislatures or governors one day agree to elect presidents by majority rule? It’s not a sure thing, but it’s more feasible than eliminating the Electoral College by amending the Constitution.