CNN has reported that the McCain camp is giving up on Colorado. If you consider Obama to be safe in every place where Kerry won plus Iowa and New Mexico (which look pretty safe and Gore carried in 2000), then Colorado alone would give Obama enough electoral votes to win.
The McCain campaign says this means they must win Pennsylvania. The problem is that Obama is ahead by almost 13 points in an average of the last 10 polls taken there.
This is not to mention that McCain would also need to prevent Obama from winning Ohio, Florida, or some combination of Missouri, Virginia, and North Carolina.
Somebody either has some serious cockeyed optimism, or the calculator is broken.