Up in New Jersey, Chris Christie notes that Democrats have already spent $1.2 million in negative ads against him – and he still leads the primary and the general-election matchup against Democratic governor Jon Corzine by healthy margins.

Here in Virginia, the Democratic Governors Association and its affiliated groups have spent nearly $3 million in negative ads attacking Republican nominee Bob McDonnell, and New York City Mayor Mike Bloomberg ran his own negative ads against McDonnell earlier this year. Yet McDonnell continues to lead all Democratic challengers by 7 to 13 percentage points, with the margin widening, not shrinking.

Theory One: It’s early, and nobody’s paying attention to these negative ads.

Theory Two: Voters have heard the exact same “he’s a right-wing extremist” argument from the Democrats for a long time, applied to a lot of Republican candidates, and they’re tuning it out. Christie and McDonnell are their own men, accomplished prosecutors with deep roots in the states that they’re running in, drawing a stark contrast with Democratic rivals whom the public deems a failure (Corzine) or flawed (the Democrats running for governor).