The evidence has been accumulating for over a year.The biggest problem has been the media jumping on events that haven't panned out which undermines the administration's efforts to make a case.
But the evidence is there; Bush only needs to present and summarize it at a time and place of his choosing.
Of course the leftists will still try to claim that Bush hid the evidence to score political points.
Hard to believe, but I know people, who aren't even leftists per se, who are convinced that Bush has already captured Bin Laden and is just waiting to spring it right before the election.
Lots of conspiracy theorists around.
I think there are lots of conspiracies, but not the same ones these people believe.