It's been found out that there was many cases of voter fraud during the 2012 election. Here is two of the cases (found on http://endoftheamericandream.com/archives/22-signs-that-voter-fraud-is-w...):
#1 According to the Election Protection Coalition, voters across the United States reported more than 70,000 voting problems by 5 PM Eastern time on election day.
#2 There were 59 voting divisions in the city of Philadelphia where Mitt Romney did not receive a single vote. In those voting divisions, the combined vote total was 19,605 for Barack Obama and 0 for Mitt Romney.