Presidents who are re-elected always get a higher popular vote percentage

than in their original election. I admit that didn't hold true for Andrew Jackson, whose popular vote percentage dropped about 1%. Before Jackson, popular vote wasn't kept track of and wasn't really meaningful. But ten Presidents have been elected and re-elected since then, and every one increased his popular vote percentage the second time.
Lincoln 39.7 to 55.0
Grant 52.7 to 55.6
McKinley 51.0 to 51.6
Wilson 41.8 to 49.2
FDR 57.4 to 60.8
Eisenhower 55.2 to 57.4
Nixon 43.4 to 60.7
Reagan 50.8 to 58.8
Clinton 43.0 to 49.2
Bush II 47.9 to 50.7

Will President Obama make it 11 in a row? I'm fairly confident that he will be re-elected, but most pundits would surely predict a tighter race than 2008. Historical trends can't be guaranteed to continue, but this is statistically a far more meaningful trend than the supposed trends about approval numbers or unemployment numbers predicting election results that we keep hearing about. The odds against the incumbent's improving his percentage ten times in a row are 1023 to 1. If we also count Jackson, the odds against it happening at least 11 times out of 12 are 170 to 1. I'm guessing Obama will get about 56% next year.

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by about 0.5%, so it wouldn't take a very large improvement to get there. If Romney is the nominee, as I expect he will be, I won't be surprised if the margin is closer, but I'd expect him Obama to get at least 54% against any of the other GOP dreamers.

It was the highest since 1984, in terms of percentage. But it still looks way less than '84. Will that ever be matched again?

Reagan '84: 58.8%, 525 Electoral Votes

Obama '08 52.9, 365 Electoral Votes

Only Tilden in 1876 lost with over 50%, but that election was so messed up it doesn't make a very good counterexample.

It will happen. With whatever numbers they decide make their policies have the best shot.

I doubt they will give him a big margin, if they do give him a victory!

I can't even see him matching his 52.9%. It will probably be a much tighter race, barring a Palin.

He'll win by a comfortable margin since Perry's message only resonates with the Tea Party. Obama will unite his base and get a bunch of independents either on his side or voting with their noses plugged. I could very well see Obama getting around 56% then.

If it's Romney, it will be a tight race. I still see Obama coming up on top, but it will be a tough election and Obama will have to make sure his base is completely with him, and he'll have to do a good job of educating moderates and independents on his proposals and positions. But, Obama will only get around 50-51% then.