The big buzz today, just over six weeks out from the iowa Caucuses, is a new ABC-Washington Post poll of the Democratic field in Iowa. For casual news consumers, the top line of this poll--Obama up by 4 over Clinton--may seem like a big, exciting shift. But actually, the same poll had Obama up back in July. The more dramatic change is that Obama's up 8 points over Edwards, though even that difference shrinks to 5 percent among the likeliest voters, and the margin of error is four-and-a-half percent.

Like last week's CBS-New York Times poll, this one shows Clinton trailing Obama and Edwards in "second-choice" support, though it does not break out supporters of those second-tier candidates who might actually have to make a second choice at the Caucuses.

The internal finding that the Post finds most significant is that Obama's now no more dependent on first-time Caucus-goers--and thus a big overall turnout--than HRC (though both are significantly more dependent on such voters than Edwards, the candidate who would probably most benefit from a lower turnout).

Meanwhile, there's a new CNN/WMUR poll of the Republican field in NH, which shows Mitt Romney expanding his lead, Rudy Giuliani and (most calamitously) Fred Thompson declining, and Ron Paul leaping into fourth place. CNN/WMUR's September poll was the one, you might remember, that sparked a bunch of "Giuliani Catches Romney" headlines. Not so much today, since Romney's lead over Rudy is 17 points, with McCain actually in second place without adding or losing support since September. Big Fred dropped from 14 percent in September to 4 percent now, and an amazing one-half of poll respondents said they wouldn't vote for him under any circumstances.

Sic transit gloria, eh Fred?