In United States presidential elections, an unpledged elector is a person nominated to stand as an elector but who has not pledged to support any particular presidential or vice presidential candidate, and is free to vote for any candidate when elected a member of the Electoral College. Presidential elections are indirect, with voters in each state choosing electors on Election Day in November, and these electors choosing the president and vice president of the United States in December. Electors in practice have since the 19th century almost always agreed in advance to vote for a particular candidate — that is, they are said to have been pledged to that candidate. In several elections in the 20th century, however, competitive campaigns were mounted by candidates who made no pledge to any presidential nominee before the election. These anomalies largely arose from fissures within the Democratic Party over the issues of civil rights and segregation. No serious general election campaign has been mounted to elect unpledged electors in any state since 1964.
An unpledged elector is distinct from a faithless elector who pledges their vote for a particular candidate before the election but ultimately votes for someone else or fails to vote at all.
Constitutional background
When the United States Constitution was written, the Founding Fathers intended the Electoral College to be a truly deliberative body whose members would choose a president (and vice president, after 1800) based on their own preferences. They also left the method for selecting the electors for each state to the discretion of that state's legislature. Other than the implied expectation that the electors vote for candidates who are constitutionally qualified to serve as president and vice president, the Constitution otherwise places no restriction on the behavior of the electors, and assumes that each is an independent agent.
The system worked without much controversy for the first two presidential elections in which George Washington was the unanimous choice for president and electors' opinions diverged only on the choice for vice president, which was widely seen to be an unimportant post. Washington was not a member of any political party, and had hoped they would not be formed. Nevertheless, "Federalist" and "Anti-Federalist" factions quickly coalesced in the United States Congress.
Once Washington announced his intention to retire after his second presidential term, U.S. politics very quickly became dominated by strong political party organizations. Even without this particular development, the reality was that electors had only one constitutional duty – electing the president and vice president, while at the same time seeking no other federal office since federal officials are constitutionally barred from serving as electors. In several states, legislatures chose electors. Among the states that selected electors by popular vote, different electoral systems were in place. Some effectively held a statewide vote for all electors – essentially the system most similar to that used in 48 of 50 states today although at this time an electoral mechanism that could effectively compel voters to vote for any particular "slate" of presidential electors had not yet been contemplated. Some states elected two electors in a statewide vote and one in each congressional district (essentially, the system used today in Maine and Nebraska) and a few states experimented with selecting presidential electors in special districts distinct from its congressional districts. More broadly, the franchise (that is, the qualifications that determined who among the adult male population was allowed to vote for state and federal legislators and, where applicable, for presidential electors) varied widely from state to state. However, no matter who was allowed to vote for electors and no matter how they were selected, the only meaningful question any prospective elector had to answer was for whom they would vote for president (and, from 1804 onward, for vice president) and the only real issues of importance to those selecting electors, beyond deciding who they wanted to become president and vice president, was perhaps whether the person or people they selected to represent them in the Electoral College could be trusted to keep their word. Thus, it rapidly became increasingly unrealistic for anyone to be elected to the Electoral College without making a trustworthy "pledge" to vote for particular candidates on behalf of those electing them.