Yup - it was fraud that caused this mess. And may happen again today.
It wasn’t vote fraud.
Yes, there was some fraud, but not enough to even scratch the surface of what happened.
Which is well-documented.
Romney had a big data GOTV system. It was called “Orca”. It imploded on election day, along with the backup plan, effectively crushing Romney’s turnout machine. This has been well described and documented, including an excellent article on Breitbart.
Obama and the Dems had big data GOTV systems as well. They were called “Narwhal” and “Catalist” (also “Vote Finder”). These performed better than expected, limiting what looked to be a collapse in Obama’s support to something manageable. This is also well described and documented, including in an excellent article on PJMedia.