The state presidential electors are chosen by the individual parties. Each state party organization has different rules how the electors are chosen.
"Presidential electors are selected on a state-by-state basis, as determined by the laws of each state. Generally (with Maine and Nebraska being the exceptions), each state appoints its electors on a winner-take-all basis, based on the statewide popular vote on Election Day." See below link for further information:
The electors in each state are elected by the popular vote in the presidential election and swear in advance to vote for the presidential candidate who wins the election in their state.
The process for selecting electors varies throughout the United States. Generally, the political parties nominate electors at their State party conventions or by a vote of the party's central committee in each State. Electors are often selected to recognize their service and dedication to their political party. They may be State-elected officials, party leaders, or persons who have a personal or political affiliation with the Presidential candidate. Then the voters in each State choose the electors on the day of the general election. The electors' names may or may not appear on the ballot below the name of the candidates running for President, depending on the procedure in each State.
Congress
Proposal for choosing presidential electors by which two electors would be selected in each State according to the Statewide popular vote and the other electors would be selected separately in each of the State's congressional districts.
Proposal for choosing presidential electors by which two electors would be selected in each State according to the Statewide popular vote and the other electors would be selected separately in each of the State's congressional districts.
Pennsylvania appointed 21 electors for each of the presidential elections of 2004 & 2008, they appoint 20 electors for each of the presidential elections of 2012, 2016 & 2020, and if the U.S. Census Bureau population projections for the year 2020 turn out to be accurate, they will be appointing 18 electors for each of the presidential elections of 2024 & 2028.
The electors are chosen by the voters of each state in the presidential election. When people vote for president, they actually are choosing the electors supporting the candidates named on the ballot.
The Electors in the electoral college represent the people who elected them. The political parties in each state choose slates of potential Electors sometime before the general election. The electoral college Electors in most states are selected by state party conventions or by the state party's central committee. In a few states the Electors are selected by primary election or by the party's presidential nominee. Political parties often choose Electors that are state elected officials, state party leaders, or people in the state who have a personal or political affiliation with their party's Presidential candidate. On Election Day, the voters in each state select their state's Electors by casting their ballots for President. In most states, the names of individual Electors do not appear anywhere on the ballot; instead only those of the various candidates for President and Vice President appear, usually prefaced by the words "Electors for." The Electors are expected to vote for the presidential and vice-presidential candidates of the party that nominated them.
In December following the presidential election, on a day set by law, the presidential electors (of the Electoral College) in each state and the District of Columbia assemble. State electors usually meet in their state's capital. The electors then cast their ballots for President and Vice President. Either by custom, or in a few states, by law, electors vote for their party's choices for the two offices. The lists of these elections are sent under seal to the president of the Senate and to the Administrator of General Services in Washington, DC.
The number of electors for a state is determined by the state's representation in Washington. That is, each state has one elector for each senator and one elector for each representative. For example, Wyoming has two senators and one member of the House of Representatives. Therefore, Wyoming has three electors.