Gallup’s poll is of US Adults, not registered or likely voters...and does not account for turn-out intensity.
The comparison should be between Sarah F of 44 and Obama’s job approval at 49. The 56 F for Obama is a red herring.
Here is why. From Matthew Dowd, a former GOP strategist, if an incumbent goes into a fall election cycle above 51% with Gallup in his job approval he has never lost re-election; if he has gone into below 47% he has always lost; and the gray area is between 47-51%.
In addition was 46/46 in a recent CNN poll and 45/46 in a Battleground poll released yesterday and Rasmussen has Obama’s job approval at 46/54 today.