Washington: US President Barack Obama's approval rating this past week was recorded at 40 percent, the lowest of his administration so far, the latest national opinion poll of the Gallup has said.

Obama's job approval rating dropped to 40 percent during the week spanning August 8-14, the lowest weekly average of his administration.

During this period, Obama's three-day rolling average also hit a new low of 39 percent for August 11-13, the first such average below 40 percent since he took office, though it recovered to 41 percent for August 12-14, Gallup said in a statement.

"With the exception of a dramatic national or international event, it is usually difficult to pinpoint the causes for the short-term ups and downs in a president's job ratings. In the current situation, it is reasonable to assume that several events of the last few weeks have played a part in depressing the public's approval of Obama," Gallup said.

It said 10 incumbent presidents have sought re-election since World War II, and none has won a second term with final pre-election job approval ratings below 48 percent.

The last two presidents who lost their re-election bids -- George W Bush and Jimmy Carter -- had job approval ratings in the 30 percent range in the fall of the election year.

"Thus, Obama's challenge is not only to move his rating back above 40 percent, but also to push it close to or above 50 percent," it said, adding that the crucial period for Obama will begin after Labor Day, given the relative quiet on the political front that should be the case before then.

Obama on Monday began a three-day bus tour through Minnesota, Iowa and Illinois.

(Agencies)

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