Wealthy liberals are finally starting to pony up, reports the Times, as George Soros is (note the phrasing) "preparing to inject up to" $100 million to two liberal grassroots get-out-the-vote groups. So the money tree is shaking loose.
Still, it seems very unlikely to me that rich liberals will combine to do anything close to the amount of money that conservatives will donate to the Super PACs. I'm told that the Obama people expect at least $600 to be spent against them, maybe $800 million. A pretty staggering amount of outside money, all dubiously labeled "educational" or "issue advocacy" or whatever it is so that Karl Rove can call Crossroads GPS a 501c4 and avoid disclosing donors.
So here's what will happen, one supposes. In swing states, citizens will be carpet-bombed--and we say this every four years, but this time, really carpet-bombed--by anti-Obama ads. The weekend sports-watcher will hardly see anything else. But here's what I wonder: When is enough too much?

Joseph Wanamaker, the eponymous (well, once, before everything was Macy's) department store scion, once famously said: "Half the money I spend on advertising is wasted. The trouble is, I do not know which half." Market research has come a long way since then, but it's still surprisingly hard to tell. Consider this research on automobile advertising.
According to this interesting piece I dug up from something called Strategy + Business, automakers spend billions every year but really aren't sure what they're doing, and they're greeted by dramatically different results:
During the six years we studied, 1998 through 2003, many brands with excess media spending did indeed grow on average in market share. But so did some of their counterparts with less spending. For example, Ford and Chevrolet both spent close to the predicted optimum levels for their brands, but with widely divergent results. The same is true for Dodge and Kia, Lincoln and Toyota, and Pontiac and Hyundai. The two factors--market share change and media spend levels in excess of the prediction by the model--did not directly correlate.
Yes, presidential candidates and cars aren't the same kind of thing. But the human brain is the human brain. There's only so much of anything it can take, and that includes attack ads. My bet is something like this: The first $300 million spent by the conservative Super PACs on advertising will be money very well spent; the next $300 million won't get them much more than the first $300 million did; and any amounts beyond that may well invite some kind of backlash. The same would apply to Democratic spending, too, of course, but the Democrats are less likely to hit the point of overkill.