So Chris Hayes (MSNBC) said: "If the Electoral College wasnʻt written into the Constitution, it would be unconstitutional." And when God was passing out brains, Hayes thought He said "drain" and his portion was washed down rabbit hole along with the rest of the worldʻs toilet water,.

The Framers were wary of giving the people the power to directly elect the President — some felt the citizenry too beholden to local interests, too easily duped by promises or shenanigans, or simply because a national election, in the time of oil lamps and quill pens, was just impractical. Some proposals gave the power to the Congress, but this did not sit well with those who wanted to see true separation of the branches of the new government. Still others felt the state legislatures should decide, but this was thought to make the President too beholden to state interests. The Electoral College, proposed by James Wilson, was the compromise that the Constitutional Convention reached.

Though the term is never used in the Constitution itself, the electors that choose the President at each election are traditionally called a College. In the context of the Constitution, the meaning of college is not that of a school, but of a group of people organized toward a common goal.

The Electoral College insulates the election of the President from the people by having the people elect not the person of the President, but the person of an Elector who is pledged to vote for a specific person for President. Though the ballot may read "John McCain" or "Barack Obama," you're really voting for "John Smith" who is a McCain supporter or "Jack Jones" who is an Obama supporter.

The function and details of how the Electoral College meets and how they vote was changed in the 12th Amendment. First, a discussion of the original plan, outlined in Article 2, Section 1, Clauses 2 and 3, then what is different today:

Each state chose a number of electors equal to the number of congress people that state had. Each state, then, got at least three electors (two Senators and at least one Representative). Electors may not be an employee or elected representative of the Federal Government. Each state was allowed to otherwise choose whomever they wish to be the Electors for that state.

Source :    https://usconstitution.net/consttop_elec.html