The Electoral College
The electoral College is the system by which the US elects its Presidents. This system uses the weighted vote of a state rather than the popular vote of the people. For a more in depth explanation of the Electoral College, click on the map below.
As you can probably see, there are a few things that might be considered to be problematic with the Electoral college. For instance, a candidate might win the popular vote, but could still lose the Presidency. Also, if there is no majority reached among the states, then the race is decided by the House and Senate. The House would decide who is President, and the Senate would get to choose the Vice President.