President John Kerry (D-MA) / Senator Barack Obama (D-IL)
Fmr. President George Bush (R-TX) / Congressman Paul Ryan (R-WI) ✓
With Bush out before his unpopular second term and Kerry taking the blame for Hurricane Katrina, sectarian conflict in Iraq, the Great Recession, and the resignation of Vice President Edwards (either because of scandal or to retire with his dying wife), it's a Republican win. However, the competitive primary is damaging and Bush bungles the campaign somewhat, making it closer than it would have been with another candidate.