Campaign advertising still matters, even in presidential elections. Although there are many other sources of information available for the active, information-seeking voter — debates, news coverage, Web sites of all stripes — those who prefer their politics later and lighter still get information from commercials.

That's why I have been such an advocate for President Obama defining Mitt Romney before he defines himself. (This is obvious strategically; the only reason the Obama campaign wouldn't do it is if it can't afford it.) In recent weeks, as predicted,  Romney has started to inch up in the polls as the stink of his primaries has started to wear off. But now there's a new smell coming from an old friend: his former firm Bain Capital, as the Obama camp unveils a new negative ad today in key industrial battleground states.

Bain is the gift that not only continues to pay dividends for Romney's Swiss bank accounts but also for his political opponents. Ted Kennedy, with Bob Shrum's skillful ad-making, first mined these waters in 1994, but the story never gets old for political strategists. It is a powerful hit on Romney that is likely to drive his negatives into the danger zone.