Into the category of Things You Don’t Have To Follow, add today’s focus on Barack Obama’s 3rd Quarter fundraising totals. Yes, $70 million is a lot of money. But it’s unlikely to matter much. If you want to know whether Obama is going to be reelected, you’re much better off paying attention to reports about the economy, or even his approval ratings. Money just doesn’t matter much in presidential general elections.

Money doesn’t matter much because most of us are partisans, and can be counted on in the end to support our party’s candidate; indeed, that’s even the case for most of those who think of themselves as independent voters. Money doesn’t matter much because presidential elections get enormous amounts of coverage in the press, and so even saturation levels of advertising tend to matter a lot less because ads aren’t as likely to convince someone how to vote when there’s plenty of other information out there. Money doesn’t matter much because it’s subject to diminishing returns; the 12th ad you see isn’t as likely to matter as much the first few.

Money certainly does matter in some campaigns — it’s just that the one place it makes the very least difference is presidential general elections. In primaries, voters with no cues from their party are searching for information and therefore especially open to persuasion. In downballot races that receive little press attention, advertising may even be able to override party loyalty, since it might be the only (other) information many voters have — especially in those races in which one candidate spends plenty and the other doesn’t.

You’re going to hear soon, especially if the GOP race deadlocks and extends into spring, that all that money Obama is raising gives him a huge advantage, just as Bill Clinton’s spending in spring 1996 supposedly destroyed Bob Dole. But as John Sides recently noted, there’s actually very little evidence that it had any effect at all.

Face it: if you want to give money to affect election results, an incumbent president (or the challenger after the nomination is decided) is about the worst investment you can make. There are lots of other better options. And as for all the breathless reporting you’re going to see about what Obama’s totals mean about how popular he is or whether he’s going to win, just forget about all of it.