President John Kerry (D-MA) / Senator Barack Obama (D-IL)
Senator John McCain (R-AZ) / Governor Tim Pawlenty (R-MN) ✓
Iraq is federalized and then partitioned into three states, leading to further conflict between the Sunnis and Shi'ites and increased confrontation with Iran. Edwards resigns following a personal scandal. 2004 DNC keynote speaker Barack Obama is Kerry's running mate, helping add some popularity back to the ticket amid economic downturn.
President McCain starts a war in Iran in 2009 in support of the Persian Spring and for fear that nuclear weapons are being manufactured, later expanded into former Iraq and then Syria to take out Iranian proxies. Decent chance that confrontation with Russian forces triggers nuclear war.