From Americablog:

In an interview, Pelosi also said she was puzzled by what she considered the president's minimalist explanation for his confidence in the new surge of 21,500 U.S. troops that he has presented as the crux of a new "way forward" for U.S. forces in Iraq.

"He's tried this two times - it's failed twice," the California Democrat said. "I asked him at the White House, 'Mr. President, why do you think this time it's going to work?' And he said, 'Because I told them it had to.' "

Asked if the president had elaborated, she added that he simply said, " 'I told them that they had to.' That was the end of it. That's the way it is."

Transcript, including punchline:

PELOSI: He's tried this two times - it's failed twice. I asked him at the White House, 'Mr. President, why do you think this time it's going to work?'

BUSH: Because I told them it had to.

PELOSI: Why didn't you tell them that the other two times?