In US presidential elections, voters vote for electors who then cast votes for the president and vice president. Typically, electors are pledged to vote for a specific candidate, but in principle it is possible (though illegal in some states) for elector to vote for any candidate.
An elector who votes for a candidate other than the one that they are pledged to is known as a faithless elector.
In 2016, there were ten faithless electors, seven of which were not invalidated; this resulted in one electoral vote for Bernie Sanders, one for Faith Spotted Eagle, three for Colin Powell, one for Ron Paul, and one for John Kasich.
How many successful faithless electoral votes will there be in the 2020 election?
Resolution will be by an official statement by a US government department, or credible media reporting if no such statement is available.