If you’ve been paying attention to this blog over the weekend, you’ll have learned that Rush Limbaugh accused Gallup of “upping the sample to black Americans to keep [Obama] up at 50%” in the polls. I remarked that, if you want to rig the polls and you’re clever–and Gallup is nothing if not clever–you can do it without resorting to racial sampling.

Alan Abramowitz adds:

It is beyond weird that Rush Limbaugh is now accusing the Gallup Poll of deliberately over-counting Democrats because the truth is that the Gallup Poll has for the past several months consistently shown a smaller Democratic advantage in party identification than other national polls.

As the table below demonstrates, of the major national polls that regularly report results on party identification, only Rasmussen shows a smaller Democratic advantage than Gallup, and only barely so.

The average Democratic advantage in party identification in the Gallup Poll since June, +6, is substantially smaller than the average in every other major national poll. In fact, no other major poll has shown that small a Democratic advantage even once during this time period. This is significant, of course, because party identification is very strongly correlated with opinions on other questions such as presidential approval, attitudes toward health care reform, and the generic ballot question. For example, Gallup recently showed Republicans leading on its generic ballot question for the first time this year-. Of the other major polls that have asked this question, all except Rasmussen have continued to show a Democratic lead on the generic ballot question.

Gallup’s results with party leaners included have shown an even smaller Democratic advantage recently. Most other national polls do not report party identification results with leaners included, but the WP/ABC does, and it has consistently shown a substantially larger Democratic advantage than Gallup. Now there is nothing unusual about “house effects” in polls but until fairly recently Gallup was considered to be in the mid-range when it came to house effects. Based on these recent results, however, it appears that Gallup now has a significant Republican lean compared with most other national polls. And because of its prestige and the frequency of its polls, Gallup also has a disproportionate influence on public and elite perceptions of the state of public opinion on major issues.