Maybe it's because the Gallup poll shows Democrat chances for retaining control of the House are far worse than Rasmussen's poll.
Usually Democrats don't like Rasmussen because of his perceived bias. But because his numbers are slightly less worse than Gallup's, they like him just fine this time around.
Yesterday, Gallup delivered its first 2010 "likely voter" poll and the results floored the political community. In the generic ballot question, which asks which party a voter would favor in a generic House contest, Gallup gave the GOP a 46% to 42% edge. But then Gallup applied two versions of its "likely voter" turnout model. In its "high turnout model," Republicans led Democrats by 53% to 40%. In its "low turnout model," the GOP edge was a stunning 56% to 38%. That kind of margin in favor of Republicans has never been seen in Gallup surveys.
But regardless of where likely voters are right now, it's a strange political year when Democrats start consoling themselves with Scott Rasmussen, whose polls they have long disparaged as being biased towards Republicans.
Despite what the polls show we must remember that the only poll that counts is the one on November 2nd. The Democrats will have no way of discounting the results of that one.