The McCain-Palin campaign's motto for the week might as well be, "All good things must come to an end." McCain's convention bounce has faded, and so too has Sarah Palin's immense initial burst of popularity. (Of course, these might not be separate phenomena.)
Several polls point to the same result: the sheen seems to be coming off the governor of Alaska. Two polls conducted early this week showed tumbles for Palin from a week before. The Hotline poll, as of Tuesday, had Palin's favorable/unfavorable numbers at 48/36 -- that is, 48 percent of respondents said they had a favorable opinion of her, while 36 percent said they had an unfavorable opinion of her. Just a week earlier, she was at 48/24. And a New York Times/CBS poll conducted Sept. 12-16 pegged her at 40/30, down from 44/22 -- as in the Hotline poll, that's a 12-point loss.
But it's the daily tracking poll by Research 2000 that shows the most dramatic result. In that poll, Palin's numbers have slipped from 52/35 a week ago to 42/46 today. Taken in terms of net approval, that's a collapse of 21 points. Research 2000, while generally well-regarded, is polling for liberal super-blog Daily Kos, so some people question the credibility of its results in this case. These numbers are, however, the most up-to-date of the three sets.
Update: A friend saw this post and sent along this critique of the Daily Kos/Research 2000 poll. In it, political scientist David Lublin points out that the survey seems to oversample Latino voters. Lublin notes that Latinos make up 13 percent of the sample, and argues that this is high because of the percentage of non-citizens within the demographic. "The share of non-citizens is especially high among the voting-age population," Lublin writes. "A much higher share of Latinos not of voting age are citizens because they were born in the U.S."
Lublin's argument is backed up by numbers from the Pew Hispanic Center. Last December, the center's Paul Taylor and Richard Fry estimated that the eligible electorate will be about 9 percent Latino this year. And if previous turnout trends continue, they said, Latinos will make up about 6.5 percent of the voters who show up on Election Day.
Because Latinos lean Democratic by about two-to-one, the oversampling is likely to cause a slight Democratic tilt to the poll. (It wouldn't explain away the downward trend in Palin's favorability, however.)