Apparently Democrats use this phrase far more often that Republicans. I agree with Stoller that its usage in Demspeak is pretty odd. In most cases, they either could say "people" (as when Clinton says "The American people know where I stand") or "Americans" (as when Edwards says "the illegal spying on the American people that this president has been engaged in") or "America" (as when Obama says "But what the American people are looking for right now is straight answers to tough questions"). Meanwhile, I don't think anyone other than grandiloquent pols and columnists ever use the phrase.
Matthew Yglesias is a former writer and editor at The Atlantic.