Affirmative Action certainly plays a role, but the Chicago Machine is the vehicle by which Obama catapulted to the national stage. It enabled (read “engineered”) his Senate seat in the Illinois legislature, and later his ascendancy to national politics. All was accomplished through Illinois Democrat politics.
BHO's entire life experience has been to take advantage of his skin color. His backers view him merely as a Trojan Horse in which to enact their agenda.
Obama won his seat in the Illinois legislature by forcing his opponents off the ballot. He won his Senate seat virtually unopposed after his primary opponent and his would-be Republican opponent were forced out of the race thanks to embarrassing information from their divorce records being leaked to the press. The only contested race he ran before 2008 was for Congress, and he lost.