PRINCETON, NJ -- President George W. Bush's disapproval rating is at 69% -- which is not only the highest of the Bush administration, but the highest disapproval rating in Gallup Poll history.

President Bush's approval rating now is at 28%, which ties for the lowest of his administration, but is not the lowest in Gallup Poll history. Harry Truman reached a 22% approval rating in 1952, and Richard Nixon had two 24% job approval scores in 1974.

In other words, although Bush's disapproval rating is the highest in Gallup history, his approval rating is not the lowest. This seeming anomaly is mostly because of differences over the years in the percentage of respondents who say "don't know/no opinion" when asked to rate a president.

Harry Truman's 22% approval rating was accompanied by a 64% disapproval rating, leaving 14% of those interviewed who did not offer an opinion about his job performance. Richard Nixon's two 24% job approval ratings in 1974 were paired with 63% and 66% disapproval ratings, leaving 13% and 10% with no opinion.

In the most recent poll for Bush, his approval rating is 28% while his disapproval rating is 69%, leaving only 3.5% (rounded to 4%) who don't have an opinion.

There is no single explanation for why the percentage who decline to give an opinion of the president's job performance is lower now than in the past. However, one hypothesis is as follows. When Gallup polled in the Truman and Nixon years, respondents may have been more likely to say they didn't have an opinion in lieu of saying they disapproved of the president. In other words, respondents who did not approve of the president's performance -- rather than flat-out saying they disapproved -- may have simply told interviewers they didn't have an opinion.

Today, as the percentage of "no opinion" responses to the presidential job approval question has declined, Americans appear to be more willing to give a negative response, resulting in the situation in which Bush's disapproval rating is at a record high while his approval rating is not at a record low.

Interviewing in the Truman and Nixon years was conducted in respondents' homes rather than by telephone, which may be related to some differences in the percentages of respondents who gave "no opinion" answers to the job approval question. But an interesting contrast is provided by polling conducted in the administration of the current president's father, George H.W. Bush, who in one poll in 1992 had a 29% approval rating -- only one point higher than his son's current approval rating. In that 1992 poll, the senior Bush had only a 60% disapproval rating, leaving 11% with no opinion, similar to the "no opinion" percentages in the Truman and Nixon polls. Yet the 1992 poll was conducted by telephone in similar fashion to polling today, suggesting that the mode of interviewing per se is perhaps not the sole explanation for the differences over the years.

It may well be that the current president Bush is simply a more polarizing figure, one who generates strong opinions in the negative direction and therefore fewer ambivalent, no-opinion responses than was the case for George H.W. Bush, Truman, or Nixon at the nadirs of their administrations.

The bottom line remains that -- perhaps for several reasons -- the 69% disapproval rating generated by the current president is the highest such rating recorded over the years in which Gallup has been measuring the public's approval and disapproval of each president's job performance.

Survey Methods

Results for the current poll, including the latest George W. Bush approval ratings, are based on telephone interviews with 1,016 national adults, aged 18 and older, conducted April 18-20, 2008. For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±3 percentage points.

Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only).

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.

To provide feedback or suggestions about how to improve Gallup.com, please e-mail feedback@gallup.com.