George W. Bush came in second, with 28 percent naming him as the worst recent president, followed by Richard Nixon with 13 percent.
The results, like those of most questions tracking presidential approval, were highly partisan. Part of what makes the numbers so bad for Obama is that the GOP respondents are slightly more united in their loathing: While 63 percent of Republicans named Obama as the worst, Democrats were split between Bush (54 percent) and Nixon (20 percent).
Asked specifically to compare Bush with Obama, voters were about evenly split, with 39 percent saying Obama is better, 40 percent saying he is worse, and the remainder saying he is about the same. By contrast, in four surveys taken during 2010 and 2011, Obama was considered the better president by a margin of 6 to 16 percentage points.
Legacy has been kind to the majority of recent presidents. Six of the past nine saw their approval ratings rise in Gallup's polling after leaving office. Bush, whose final approval rating in the Gallup poll as president was just 34 percent, saw his numbers rise 13 points by 2013.
The survey gives Obama a 40 percent approval rating. The president's numbers, which held stable in the mid-40s for much of the year, dipped slightly in late June, just after the news of intensifying violence in Iraq.
Forty-five percent of voters now say the country would be better off if 2012 GOP presidential candidate Mitt Romney had won, while 38 percent say it would be worse.
Quinnipiac polled 1,446 registered voters June 24 to June 30, using live interviewers to place calls to both landlines and cell phones.