The presidency is determined not by the popular vote but by the electoral college. President Bush could still lose the popular vote and still win a second term like he did in 2000!
Look at
Dales Electoral College Breakdown 2004. He does a good analysis of the probable EC votes in 2004.
If you look at states that are STRONG and SAFE for the 2 candidates, it's BUSH 127 and KERRY 61.
If you include states that are LEANING, then it's BUSH 222 and KERRY 209.
Among the states that are SLIGHT, they are all BUSH (+77). That leaves 30 EC votes that are tossups.
