First, let's discuss the new Pew release, and attempt to do so without freaking out.  It presents grim reading for at least two reasons: the four point Romney lead, and that Pew has had a consistent Democratic lean, relative to the aggregate averages, this entire cycle.  Indeed, Silver notes The Pew poll, however, may well be the single best polling result that Mr. Romney has seen all year. It comes from a strong polling firm, and had a reasonably large sample size. Just as important is the trendline. Pew's polls have been Democratic-leaning relative to the consensus this year; its last poll, for instance, had Mr. Obama 8 points ahead among likely voters. So this represents a very sharp reversal. As it's important to not fall into the trap of focusing on confirmatory evidence to the exclusion of equally valid contrary evidence, it's likewise not healthy to overly concentrate on one negative national poll to the exclusion of the weight of extant evidence.  In other words, I didn't start doing back flips following the September Pew release showing an eight point Obama lead, and I'm not marching to the liquor store to buy out their stock of whisky because of this one. There are legitimate, and less legitimate reasons to be weary of this one poll; John Sides does a solid job of pointing out some examples of both.  One reason attracting attention is the underlying partisan identification of the sample.  The most recent, October Pew sample had 31% Democrats