The percentage of respondents who said they disapproved of his performance also remained unchanged at 47 percent in the Gallup Daily tracking poll.
Gallup noted all incumbent presidents who have been elected to a second term had a 50 percent or higher average approval rating by February of the election year. In every case except former President George W. Bush, incumbents who went on to win had a 50 percent or higher approval rating through Election Day.
The poll found 50 percent of respondents said they considered Obama's presidency a failure.
Most Democrats said they considered Obama's presidency a success, while most Republicans called it a failure. Among independents, a slight majority called his presidency a failure.
The poll is based on telephone interviews conducted with 13,999 adults Feb. 1-29. The margin of error is 1 percentage point.
State rests in Michael Dunn case