If Hurricane Katrina takes place one year earlier, less than 3 months before the election, you can be sure the Bush administration would have handled this crisis with the utmost urgency, and would have done everything in their power to ensure the crisis was handled in an exemplary manner.
They would have used the crisis as a rallying cry for the nation to support Bush and the great work the administration was doing in the crisis. They would have urged Americans to come together, under the leadership of George W Bush, and to work together, united and strong, in combating this crisis.
Voters would see plenty of footage of President Bush, Vice President Cheney, and other administration officials, personally on site at devastated areas, and talking to and helping the victims. These photo ops would be turned into campaign ads for the Republicans.
America gets behind Bush in the crisis, which happens shortly before the election, and Bush wins by a much larger margin.
One must keep in mind the poor performance of Louisiana Democratic Governor Blanco and New Orleans Democratic Mayor Nagin. Bush would not reference this, however, it would get plenty of reference from others in the campaign.
One must also keep in mind that Kerry was not a particularly great candidate.
I noticed this is post 1776 for me. Defining date in U.S. history, not my post, the year.
Oh, your post is pretty good as well. -_-