Yes, the President has already tried the surge/escalation tactic in Iraq more than once. And yes, the tactic failed in the past. But he wants another chance.
Jon Stewart summed it up pretty well in this seventeen second clip from the Daily Show:
UPDATE (3/30/2007): Unfortunately, the video was removed from YouTube. Sorry!
Pelosi’s conversation with Bush about the “surge”:
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?
[Source: AMERICABlog and DailyKos]