CHICAGO (AFP) – Democratic White House hopeful Barack Obama on Wednesday bemoaned the "irrational despair" afflicting tumbling stock markets, and said President George W. Bush was too weak to fix the crisis. Obama played off a famous remark that 1990s asset values were subject to "irrational exuberance" by former Federal Reserve chairman Alan Greenspan, to sum up the depths to which today's markets have stooped. "In the same way that I think Greenspan, the former Fed chairman, talked about irrational exuberance, we now have irrational despair," Obama said, when asked why a 700 billion dollar US Wall Street bailout signed...