But here’s the thing: All that spending hasn’t moved a lot of needles.

Polls show Brown’s unfavorable rating has only risen slightly since the spending began. He still has a healthy lead over Republican Josh Mandel. Kaine advisors haven’t seen his unfavorable numbers creep up, and he’s only just started telling his side of the story in paid advertising. Super PAC spending played a big role in the Republican presidential primary and in several Senate GOP primaries earlier this year, but it’s hard to find a concrete example in a general election matchup in which an outside group has really shaken up a race.

Candidate advertising has so far proven more effective than independent spending, especially advertisements that feature a candidate speaking directly to the camera.

House races are a different story. Both sides have only recently started advertising in those contests, and so far Republicans have a pronounced advantage. The National Republican Congressional Committee has outspent the Democratic Congressional Campaign Committee by a more than two-to-one ratio since September 1. That gap will narrow, but it’s clear from early spending that Republican outside groups have the advantage.