Describe the power to pick a president

The power to "pick" the president is in the hands of the electoral college, which has over 500 members, and whose only function is to elect the president (and vice-president.)

The electoral college should, but is not obliged to, vote according to the popular vote in the state, and also usually choose to give all votes to the winning candidate. There have been very few instances of electors voting against the expectations of the voters.