Josh Marshall on Obama's chances in 2012:
People simply don't appreciate how seldom elected presidents get denied reelection. By my count, it's only happened three times in the last century. Carter, the first President Bush and Herbert Hoover. (If you come up with someone I'm missing I'll be terribly embarrassed. But please let me know.)
Actually, Josh is understating things. In general, Americans don't turf out parties from the White House in less than eight years. Hoover and Bush Sr. were both voted out after their party had held the presidency for 12 years.
The only exception to this rule in the past century is Jimmy Carter. There have been a couple of other close calls (Wilson in 1916, Bush Jr. in 2004), but that's it. 1980 is the only year in which a party got thrown out of the White House after only four years.
If the economy is in decent shape, Obama will win reelection. If it sucks, he's vulnerable. That's pretty much the shape of things.