My Little Pony XXXIX: There is no Pegasus Mafia!

[Eakin]

Twilight is by far the best-educated, but... well, there is the whole "Her response to stress is to cast horrible forbidden black magic to control the minds and bodies of those around her" issue.

In B4 cheap shot at the Bush administration and the Patriot act!

Pinkie Pie would plunge the nation into a permanent Depression by declaring every day a national holiday.

Irony! not really, but the cheap Alanis Morriset type at least

Which is why I voted for Rainbow Dash. Because that way we can accept that catastrophe is going to happen and prepare accordingly/take bets on which one. The others may or may not cause disaster, Rainbow definitely will and, moreover, it'll definitely be awesome.

Rainbow Dash: The Most Reliable Candidate

So she starts some kind of international incident, her approval rating drops to 20%, and she's defeated in 2016 by President Fluttershy who hands over Equestrian sovereignty to the first world power to request it with "pretty please with sugar on top?"

EDIT:

Twilight WOULD work, however, if she were to go with her instincts and set up a Wilson administration. First among equals with the cabinet, she seems to be good at attracting oddly specific talent, after all.

I actually see her as an awesome crisis-era president, putting together a ragtag group of misfits team that somehow functions way better than it has any right to, a la Lincoln.

Sure, she'd get bogged down in the swampy, divisive domestic policy issues. But the girl's a born leader when the horse apples hit the fan. And she'd organize the labyrinthine government bureaucracy in two shakes of her tail.