The part where it doesn't work.
This kind of thing has been repeated ad nauseam throughout this thread. It's amazing. No matter how many times solid proof is presented that the first stimulus DID, in fact, work, it still keeps being repeated.
I have an objection of my own to Obama's proposal, and it's the same objection I had to the first stimulus: It's too small. It's not enough. It will work, just as the first stimulus did, but it won't work well enough -- ditto -- and for the same reason. (The first stimulus was designed to create some 2-3 million jobs when we needed 10-12 million. It worked exactly as designed.)
If you want a clear idea of what kind of stimulus spending will actually revive the economy when it's in a depression like this, and what kind of stimulus spending will just have the motor cough and rumble a little without generating a sustained start, go back to the last depression we had.
Inadequate stimulus = FDR's tepid spending on work-relief and similar programs.
Adequate stimulus = what was spent to fight World War II.
Apply the lesson forward.
Parts of it may have worked. Creating jobs of substance was a failure and Obama admitted that. We are talking job creation right?