A new national poll shows Barack Obama’s once-healthy lead shrinking to a hair’s width, suggesting his defensive performance at the Wednesday debate in Philadelphia may have hurt him.

The fresh numbers come as Hillary Clinton calls on Obama to quit whining about his supposed unfair treatment at the debate. Her campaign already has claimed Obama is trying to cover up an “awful performance” by saying he was hammered with petty political questions.

The Gallup daily tracking poll, taken from Tuesday to Thursday, indicates viewers may have had similar assessments.

The poll showed Obama with just a three-point national advantage over Clinton, 47 percent to 44 percent. A few days ago, Obama had an 11-point lead in the same poll.

The survey of 1,209 registered voters found that Obama now leads Clinton by nearly 20 points, or 54 percent to 35 percent, among registered Democrats and those who lean Democratic nationwide. The previous Newsweek poll, conducted in March after Clinton's big primary wins in Ohio and Texas, showed the two Democrats locked in a statistical tie (45 percent for Obama to 44 percent for Clinton). The new poll puts Obama ahead among women as well as men, and voters aged 60 and older as well as younger voters.