There is a saying in litigation that one argues the facts when the facts are on one’s side, the law when the facts aren’t, and attack the character of witnesses when neither the law nor the facts support one’s case.  Apparently, the same holds true in politics.  Politico’s Alex Isenstadt reports that Democrats finding themselves hammered in the polls have decided to blame not their radical agenda or the failure of their economic polices, but the pollster for reporting the findings:

Democrats are turning their fire on Scott Rasmussen, the prolific independent pollster whose surveys on elections, President Obama’s popularity and a host of other issues are surfacing in the media with increasing frequency.

The pointed attacks reflect a hardening conventional wisdom among prominent liberal bloggers and many Democrats that Rasmussen Reports polls are, at best, the result of a flawed polling model and, at worst, designed to undermine Democratic politicians and the party’s national agenda. …

While Scott Rasmussen, the firm’s president, contends that he has no ax to grind — his bio notes that he has been “an independent pollster for more than a decade” and “has never been a campaign pollster or consultant for candidates seeking office” — his opponents on the left insist he is the hand that feeds conservative talkers a daily trove of negative numbers that provides grist for attacks on Obama and the Democratic Party.

Nothing, however, sets off liberal teeth gnashing more than Rasmussen’s daily presidential tracking polls, which throughout the year have consistently placed Obama’s approval numbers around 5 percentage points lower than other polling outfits.

“He polls less favorably for Democrats, and that’s why he’s become a lightning rod,” said Charles Franklin, a University of Wisconsin political scientist who studies polling. “It’s clear that his results are typically more Republican than the other person’s results.”

None of the critics have any substantive complaints about Rasmussen’s methodology.  The entire article, fueled mainly by complaints from left-wing apologist Media Matters, consists of gripes about the results of Rasmussen polling.  Isenstadt notes that liberal pollster Nate Silver gave Rasmussen the nod as the third-most accurate pollster in predicting outcomes of elections.  They beat most of the pollsters in 2009’s New Jersey gubernatorial election, for instance, and have a long track record of highly accurate predictions.

The complaint comes from the difference in results between Rasmussen and other national pollsters, such as Gallup.  However, they use two different sampling techniques: Rasmussen polls likely voters, while Gallup and others poll adults until the final few weeks before an election.  The former is much more predictive for elections, while polling a general population of adults is the least predictive sampling technique.  And that difference gives Rasmussen an advantage that has already been seen this year.  Rasmussen first detected the erosion of support for Obama and ObamaCare in late June, an erosion that other pollsters corroborated in the fall as discontent spread from the politically aware to the general population.

There are other differences that are less innocent.  Isenstadt notes the difference in Real Clear Politics’ polling index between Rasmussen and the rest of the pollsters RCP tracks.  However, RCP includes in those averages polls conducted by media outlets like the New York Times and CBS, and ABC and the Washington Post, that routinely use double-digit gaps between Democrats and Republicans in their sample.  I have reported on the reliance of samples with gaps between 12 to 16 points favoring Democrats, a ridiculous sample considering Obama won his presidential election by seven points nationwide, and that with significant Republican crossover.  When ABC and the Post reduced their sample gap to six points, arguably an accurate representation of the electorate, Obama’s numbers plunged across the board.

And along those lines, the picture looks like it might get worse anyway:

In December, the number of Americans identifying themselves as Democrats fell to the lowest level recorded in more than seven years of monthly tracking by Rasmussen Reports.

Currently, 35.5% of American adults view themselves as Democrats. That’s down from 36.0 a month ago and from 37.8% in October. Prior to December, the lowest total ever recorded for Democrats was 35.9%, a figure that was reached twice in 2005. See the History of Party Trends from January 2004 to the present.

The number of Republicans inched up by a point in December to 34.0%. That’s the highest total for Republicans since December 2007, just before the 2008 presidential campaign season began.

However, the number of Republicans in the country is essentially no different today than it was in November 2008 when Barack Obama was elected president.

The change since Obama’s election is that the number of Democrats has fallen by six percentage points and the number of voters not affiliated with either major party has grown by six. The number of adults not affiliated with either party is currently at 30.6%, up from 24.7% in November 2008.

That puts the partisan gap at around 1.5%.  How many of the polls from media outlets will show this kind of gap in the sample?  How many will keep the sample gap to single digits?  Rasmussen has so far been proven correct by subsequent polling, even those desperately seeking massive Democratic imbalances.