In 2010, Nate Silver of The New York Times’ blog FiveThirtyEight wrote the article “Is Rasmussen Reports biased?”, in which he mostly defended Rasmussen from allegations of bias. However, later in the year, Rasmussen's polling results diverged notably from other mainstream pollsters, which Silver labeled a "house effect." He went on to explore other factors which may have explained the effect such as the use of a likely voter model, and claimed that Rasmussen conducted its polls in a way that excluded the majority of the population from answering. Silver also criticized Rasmussen for often only polling races months before the election, which prevented them from having polls just before the election that could be assessed for accuracy. He wrote that he was “looking at appropriate ways to punish pollsters” like Rasmussen in his pollster rating models who don’t poll in the final days before an election. In June 2012, Silver wrote that "Rasmussen Reports, which has had Republican-leaning results in the past, does so again this year. However, the tendency is not very strong – a Republican lean of about 1.3 points." Silver ranked Rasmussen Reports as having the third lowest house effect of the 12 polling firms that Silver analyzed.
After the 2010 midterm elections, Silver concluded that Rasmussen's polls were the least accurate of the major pollsters in 2010, having an average error of 5.8 points and a pro-Republican bias of 3.9 points according to Silver's model. He singled out as an example the Hawaii Senate race, in which Rasmussen, in a poll completed three weeks before the election, showed incumbent Daniel Inouye only 13 points ahead, whereas in actuality he won by a 53% margin – a difference of 40 points from Rasmussen's poll, or "the largest error ever recorded in a general election in FiveThirtyEight’s database, which includes all polls conducted since 1998." Silver was criticized for his 2010 pollster ratings. Conservative polling analyst Neil Stevens wrote, "after the primaries [Silver] said Rasmussen was in his crosshairs for ducking out on a number of races by not polling primaries. According to Silver’s own chart though, Rasmussen polled twice as often as the second place firm, and is still Silver’s primary target", and "Silver can’t even keep consistent his reasons for hating Rasmussen Reports." Mark Blumenthal, publisher of Pollster.com, wrote that Silver's methodology, in which he awards bonus points to pollsters based on their membership in the National Council on Public Polls and their endorsement of the American Association for Public Opinion Research Transparency Initiative, "appear to significantly and dramatically alter rankings prominently promoted as "pollster ratings," ratings that are already having an impact on the reputations and livelihoods of individual pollsters. That's a problem." Blumenthal noted, "My bottom line: These sort of pollster ratings and rankings are interesting, but they are of very limited utility in sorting out "good" pollsters from "bad."
Time magazine has described Rasmussen Reports as a "conservative-leaning polling group." The Washington Post called Rasmussen a "polarizing pollster." John Zogby said that Scott Rasmussen has a "conservative constituency." The Center for Public Integrity listed "Scott Rasmussen Inc" as a paid consultant for the 2004 George W. Bush campaign. The Washington Post reported that the 2004 Bush re-election campaign had used a feature on the Rasmussen Reports website that allowed customers to program their own polls, and that Rasmussen asserted that he had not written any of the questions nor assisted Republicans.
Rasmussen has received criticism over the wording in its polls. Asking a polling question with different wording can affect the results of the poll; the commentators in question allege that the questions Rasmussen ask in polls are skewed in order to favor a specific response. For instance, when Rasmussen polled whether Republican voters thought Rush Limbaugh was the leader of their party, the specific question they asked was: "Agree or Disagree: 'Rush Limbaugh is the leader of the Republican Party — he says jump and they say how high.'"
Talking Points Memo has questioned the methodology of Rasmussen's Presidential Approval Index, which takes into account only those who "strongly" approve or disapprove of the President's job performance. TPM noted that this inherently skews negative, and reported that multiple polling experts were critical of the concept.
A New York Times article claims Ramussen Reports research has a "record of relying on dubious sampling and weighting techniques.""