Superdelegates

Wikipedia says:

Superdelegates are delegates to a presidential nominating convention in the United States who are not legally bound by the decisions of party primaries or caucuses. Superdelegates are current elected officeholders and current party officials as well as former elected officeholders and former party officials. They are sometimes referred to as "unpledged delegates," but some unpledged delegates are not superdelegates[citation needed]. In addition, some elected officeholder delegates and party official delegates are pledged.

Superdelegates were first appointed in the 1970s, after control of the nomination process in the Democratic Party effectively moved out of the hands of party officials into the primary and caucus process. The aim was to grant some say in the process to people who had been playing roles in the party before the election year.

The Republican Party has 123 similarly automatically appointed delegates, members of the Republican National Committee. Including these appointees, the Republican Party has 463 unpledged delegates out of a total of 2,380 delegates.