There were questions about Rmoney's page and it's true number of likes. A lot of people who simply checked the site out found themselves being reported to all their friends as having "liked" the Rmoney page even though they never hit the like button or even supported Rmoney in any way.
Rmoney also paid a metric shit ton of cash to promote the page all over the place. I'm a staunch Democrat and I had that creepy smiling Rmoney come up on my feed every single day for months before the election even though I reported it as spam.
So glad I never have to see that again.

Starting a few months ago, Facebook started cracking down on inauthentic Likes, whether that means dummy accounts or just ones that were gained through deceptive practices, I'm not really sure. The same thing happened to Zynga, Lady Gaga, and the Simpsons.

That could account for a lot Romney's declining Likes. Then again, there's probably a ton of people out there that just don't want the dude that lost hanging out on their Facebook page.

What @1 said. He kept showing up on all my fake FB accounts too.

I'd heard about this and was a bit skeptical, but when you go to his FB page and keep hitting refresh you can see the number going down! Do the same to Obama's and you can see it going up.

If FB were deleting fake likers, they would probably do it in bulk, and it wouldn't show up as a "slow decline" like the linked real-time graph.

Paul Ryan's page is also loosing "likes" at a slower pace.