Go, Costco! Go, Costco!

We've been telling you this for a while: Costco contributes to Democrats. Wal-Mart/Sam's Club donates to Republicans. How are customers voting? With their feet - big time!

Consumers vote by shopping. And so far this year, they're voting more for Costco than Wal-Mart, yet another illustration of the Two Americas shopping theme. Costco's customers plainly have cash to spend. For the four weeks ended Aug. 1, Costco's same-store U.S. sales rose 9 percent; in the 48 weeks ended Aug. 1, they were up an impressive 10 percent. At Wal-Mart, the registers haven't been ringing quite so loudly. In its most recent four-week sales period, same-store sales rose a meager 2.4 percent. For August, Wal-Mart sees same-store growth of between 2 percent to 4 percent - about the same growth rate as the economy, if not slower.

So far this year, the Democratic-leaning chain has also been winning in the forum in which investors vote on company's future prospects. Over the long-term, Wal-Mart has done far better than Costco. But look at charts showing the relative two-year and one-year performance (fittingly, Costco is the blue line and Wal-Mart the red), and the Democratic discounter has been kicking the tar out of the Republican discounter.