A new public opinion poll finds President Bush's approval rating sinking to an all-time low.

Only 39 percent of those surveyed in the Washington Post-ABC News poll said they

George W. Bush pauses during speech in Norfolk, Virginia, Friday

approve of the president's overall job performance. That figure is down from 42 percent in the Post-ABC poll last month, and down from 52 percent the week of Mr. Bush's second inauguration in January.

The poll of 600 Americans was taken Friday and Saturday, after former top White House aide Lewis Libby was indicted on criminal charges related to the probe into who leaked the identity of a secret CIA operative. The poll found that 55 percent of Americans believe the Libby case indicates broader ethical problems in the White House. Forty-one percent said the case was an "isolated incident."

The survey has a four-point margin of error.