31% (USA Today/Gallup)

From USA Today:

President Bush's approval rating has slumped to 31% in a new USA TODAY/Gallup Poll, the lowest of his presidency and a warning sign for Republicans in the November elections.

[...]

Bush's fall is being fueled by erosion among support from conservatives and Republicans. In the poll, 52% of conservatives and 68% of Republicans approved of the job he is doing. Both are record lows among those groups.

Alright, really... time to get to work...