Voter Fraud vs Voter Suppression

Statistically, there has been almost no voter fraud on the small scale, and none at all on the large scale. But that's the thing. It's all a matter of scale. 

Looking back at the history, you can see that approximately 126 million people voted in the 2012 elections. Looking at the totals per candidate, we see that 65 million people voted for Barack Obama in 2012 and only 60 million voted for Mitt Romney. There were other votes cast but they were for minor candidates and not really significant. Now consider with me -- in order to "rig" an election or reverse the will of the people, it would be necessary to conjure up some five to six million votes, spread out among the several states.
It would be necessary not just to have one scheme, say, hacking voting machines , because not all states use the same voting system. Some use paper ballots, some use punch cards and one -- Oregon -- uses mail in ballots. All the people needed to do all that forging, faking or whatever. They would all have to keep their mouths shut. You're talking about hundreds of people, all of whom have to be paid, moved around , equipped and fed. Then they all have to keep silent, or (for the more sinister-minded) silenced. The idea is just not practical, not even for someone with millions to spend. But then there is the other side of the coin -- why bother faking votes if you can simply make those people who are unlikely to vote your way stay away from the polls. This has been done many times, mostly against the poor, blacks or elderly. The ways to keep people from voting are many. Consider such laws as Poll Taxes, Voter tests  -- asking someone to name every county clerk in the state, for example -- voter ID laws that require picture ID that you have to drive a ways and pay a non-trivial fee to obtain. For example, ruling that student IDs are not valid, but hunting licenses are. Then there are less legal and actually illegal means. Like the one the Republican party did in 1981 in New Jersey. The GOP flooded NJ with "Ballot Security Observers", many of whom were off-duty police officers who were openly armed and wearing "ballot security" armbands. They brought with them 4ft tall signs with big giant warnings "It is a CRIME to violate Federal Election LAW, and the penalties included. They were sued in court by the Democratic Party, and lost. Since then the GOP national has been under a consent decree prohibiting them from any such activities. Perhaps they thought the 1981 New Jersey state elections were worth it.
So here's the point : Actual voter fraud on a large enough scale to tip the balance of a national election is impractical to the extreme, but voter suppression, either by law or by illegal means on a local scale is quite possible and (regrettably) very likely. It can be argued that voter suppression is going on right now, in several states.