Bachmann and the polls

Her campaign boasts, via email:

Our campaign’s rising poll numbers have not gone unnoticed. The latest Iowa poll has our campaign in second place, just behind Mitt Romney and ahead of Rick Perry.

David Weigel questions:

Which poll? The e-mail doesn't say, but the only new Iowa poll to come out recently is this one, from the American Research Group. Sure enough, it has Mitt Romney in first place with 21 percent, Bachmann in second place with 15 percent, and Perry in third with 14 percent. One problem: ARG conducted another Iowa poll in July. Back then, Bachmann was leading in Iowa with 21 percent, to 18 percent for Romney and 2 percent for the then-theoretical Perry campaign.