One word: Obama.

From NY Times:

He arrived here for what seemed like it could be a big moment. Mayor Michael R. Bloomberg, eyeing a third-party presidential bid, joined Republican and Democratic elders at a forum to denounce the extreme partisanship of Washington and plot how to influence the campaign.
But even as the mayor gathered on Monday with the seasoned Washington hands on the campus of the University of Oklahoma, the surging presidential campaign of Senator Barack Obama seemed to steal energy from the event and set off worry elsewhere among Mr. Bloomberg’s supporters.

Mr. Obama has stressed that he wants to move beyond gridlocked politics and usher in an era of national unity. A key organizer of the effort to draft Mr. Bloomberg for a presidential run acknowledged in an interview on Monday that that Mr. Obama’s rise could be problematic.

Still, bi-partisanship is Bloomberg’s schtick, and, at the very least, he’s driven it into the political zeitgeist with the threat of a billion dollar indy bid.

In the end, isn’t that a success?

Politics Why Bloomberg Will Not Run