How the Electoral College Works
This may sound bizarre, but this is exactly what takes place during a U.S. presidential election. By voting for a Republican presidential candidate, for example, you are really voting for a member of the Electoral College who is expected — but not required — to vote along party lines, too.
The votes of the Electoral College, comprised of 538 electors divvied up by state, elect the president weeks after Americans vote in a presidential election.
State legislatures are responsible for nominating electors. The process can actually differ from state to state. In general, though, the two most common ways are:
The elector is nominated by his or her state party committee (perhaps to reward many years of service to the party).
The elector campaigns for a spot and the decision is made during a vote held at the state's party convention.
Usually, electors are people who are politically active in their party (be it Democrat, Green, Libertarian, Republican or Independent) or connected to the political arena. This includes political activists, party leaders, elected officials of the state and even people who have personal or political ties to the presidential candidates.
And while the Constitution makes no mention of qualifications that must be met to become an Electoral College member, it does determine an Electoral College member cannot be:
a member of Congress
a high-ranking U.S. official in a position of "trust or profit," which refers to a member of Congress accepting an appointment to executive office
someone who has "engaged in insurrection or rebellion" against the U.S. [source: U.S. National Archives and Records]
https://people.howstuffworks.com/electoral...

N.B.
"State legislatures are responsible for nominating electors."