Time's Mark Halperin,
writing on that site's 'The Page' blog (see source article for more details):
1. A clear, consistent, constant message frame — change...
2. A strategic vision of how to win that hasn’t changed since day one...
3. The ability to arouse unqualified pride, excitement, and righteousness in his supporters...
4. A coalition no one has ever put together before in a Democratic nomination fight...
5. A candidate with the skill to both write and deliver moving, eloquent, historic-feeling and momentum-inducing speeches...
6. A tight-knit staff that never fights with each other publicly and rarely in private...
7. No single, dominant strategic thinker who sets the campaign agenda...
8. A candidate who trusts his staff...
9. A candidate with an uncanny natural sense... of timing, pacing, rhythm, and tone...
10. A candidate who generally has fun on the campaign trail...
11. Less bureaucracy...
12. The ability to control most leaks, and roll out endorsements...
13. The ability to raise millions...
14. True grassroots organizing, often without direction from headquarters...
15. A home base in Illinois...
16. An electorate that seems oddly indifferent to conventional norms of preparedness for the job of commander-in-chief...