Obama's best quarterly average to date was during his first quarter in office, when he averaged 63 percent approval, and his worst so far was 41 percent during his 11th quarter, results released Monday indicated.
Gallup said Obama began his 18th quarter with a rally after the Boston Marathon terrorist attacks, when his approval rating was at or above 50 percent from late April through early May.
His approval rating held below 50 percent for most of the rest of May and nearly all of June, the Princeton, N.J., polling agency said.
Historically, Obama's 18th quarter average was neither the best nor worst for post-World War II presidents who served that long, Gallup said. Rather, the pollster said, it was typical and similar to 18th quarter averages for Harry Truman, at 48.7 percent, and George W. Bush, at 47.3 percent.
Results are based on nationwide telephone interviews with 45,256 adults conducted April 20-July 19 as part of the Gallup Daily tracking survey. The margin of error is 1 percentage point.