The Democrats pounced on a moment of weakness in America. They took advantage of an extreme (and extremely rare) condition in the populace in which anybody they threw up there would have defeated the Republican nominee. Knowing this, they installed the most radically leftist world leader in history. His efforts (or those by his handlers) haven't been entirely successful because he's a retard who doesn't know anything about American governance or the American people. But an idiot swinging around such a massive club can still do a lot of damage.
I don't think the situation is reversed this time. I don't think Obama can be defeated by just anyone. Duke, for instance, would never win a presidential election against Obama and I'm certain that Paul would never win with Duke as his running mate. The GOP would violate their own rules and have a "recall nomination" or some such BS.
Who should Paul choose?
Impossible to say. Singular polls are mostly fraudulent. And, in certain years (ex. 2004), the entire range of them will trend outside of reality. If Ron Paul believes he has good information, though, he should act in accordance with tradition. If the polls are close before he makes his selection, he should pick a non-threatening VP candidate who has never made a ripple in the national consciousness, but whose positions he can be certain of privately. After all, the Vice President just isn't that important in most terms. The most important thing is for Paul to reach the White House. If, however, victory seems certain (Obama polling in the teens, perhaps), then Paul should shoot for the Moon and pick a running mate who, in any other year, would stir up the media and left-wing dreck to such an extent that they would set records for voter participation. I don't know who that would be. I don't even know that such a candidate exists in this country (outside of Duke). I know that the left hates Tancredo with a passion. I believe his claims of wanting to close the border and limit even legal immigration. His other positions align well with mine. A choice more palatable to both sides (who still wouldn't be acceptable to the left in a close year) would be Paul Ryan. There may not be anything special about him when it comes to his other positions, but he does seem sincere about reducing the size of the Federal Government. Starving Washington D.C. is, in my opinion, a net good on its own, regardless of the additional outcomes.
We have to win the GOP nomination first, though. And the polls are looking good for Ron Paul on this day.