It seems Senate Inferiority Leader Harry Reid (Jackass-NV), called President Bush a "loser" in front of an audience of high schoolers.
The equally infantile responses seem to flow into one's mind, don't they?
"I know you are, but what am I?"
"It takes one to know one!"
"Mr. Pot, meet Mr. Kettle!"
But I like this one the best:
Want to see a real loser, Senator Reid? Just find the nearest mirror!
Hat-Tip: Betsy Newmark via Lorie Byrd at PoliPundit