If McCain doesn't win Ohio (20), then his chance of winning goes from 40% to 0.01%.
Other crucial states that the Republicans needs to win;
Florida (27) - high chance of winning against Obama, a real dogfight if its against Clinton
Wisconisin (10) - high chance of winning against Clinton, an underdog against Obama
Colorado (9) - high chance of winning against Clinton, should win against Obama as well though
Arkansas (6) - No contest if against Obama, but could be a close contest against Hillary
Plus one of
Nevada (5) - McCain should
win here, unless Democrats put heaps of effort into here
New Hampshire (4) - McCain should in here, especially if he goes on with the message that his run to the Presidency started there.
The more the Wright controversy goes on the more it hurts Obama, and the Republicans - as Clinton does seem to be the strongest candidate of the three right now