whether Barack Obama was fully vetted in 2008 during the Democratic primary and general election. As it happened, fortuitous circumstances enabled Obama to avoid being placed under the level of scrutiny such high-level campaigns normally entail. There are a number of avenues of attack against Obama's character that remain unexplored. But would be it be wise for Mitt Romney's campaign to take advantage of these?
The short answer is no. Obama is largely immune against personal attacks, even if they involve things most voters don't already know about Obama. Why is Obama immune? Because by the time voters go to the polls in November, he will have been president for nearly four years. Voters may not know Obama's history, but they do know about his four years in office, and they will make a judgment about Obama based on his record.
Issues of character and personality speak to the baseline qualifications for being president. In other words, when someone makes personal attacks against a presidential candidate, what they are actually saying is, "he can't be president," or "he is unqualified for the office," or "he would do terrible things as president."
These issues can only be raised when a candidate runs for president the first time, not when he is running for reelection. After all, one can't plausibly claim "he can't be president" if he has already been president for four years. The question of whether the person is qualified for the office has already been litigated.
The same goes for the kinds of personal attacks aimed at stoking fears about what kind of president the candidate would be. For example, opponents of Obama may raise questions about how radical Obama was in his early career, and whether he was dedicated to socialism. Those attacks would have made sense in 2008; they would have made voters wonder whether Obama would govern too far to the left or be more liberal than his campaign suggested. But in 2012, there is no question of how Obama would govern, because he's already done it.
And what about the other side of the coin--is Romney also immune from personal attacks? The answer is no. Romney has not yet been president, so it's an open question whether he's qualified, and what kind of president he would be. The Romney campaign and the Obama campaign will both attempt to answer those questions. Obama's campaign will make personal attacks against Romney, and it will be Romney's job to defend himself.
Is that fair? Not really. It's one of the advantages that an incumbent president has over his challenger. Perhaps it explains, in part, why incumbent presidents are reelected a bit more often than they are defeated. However, while incumbents may be immune to speculative attacks about how they might govern, they are entirely vulnerable to attacks about how they did govern. Obama's record is fully open to attack.