虽然不常见，但有先例

"There is no federal law or constitutional provision requiring electors to vote for the party that nominated them, and over the years a number of electors have voted against the instructions of the voters. The most recent example of a faithless elector was probably an accident:  in 2008, a Minnesota elector nominated by the Democratic Party cast a ballot for John Edwards, the vice presidential running mate of John Kerry. It is not common for an elector to vote for the other party's candidate, however:  remember that most electors are selected by the political party for their party loyalty, and many are party leaders. The last time an elector crossed party lines was in 1972, when an elector nominated by the Republican Party cast his ballot for the Libertarian ticket."