For the first time in years, Mayor Michael R. Bloomberg finds himself governing New York City from a most unaccustomed vantage point: Vulnerability.

Ninety million dollars and a near-constant loop of negative commercials about his opponent later, the mayor ended election night in possession of a surprisingly modest margin of victory  far narrower than pollsters had predicted and with 100,000 fewer votes than he won in 2005. This could have profound implications for the tenor of a third Bloomberg term, not least that it is likely to hinder the mayor’s well-honed ability to cow Democrats and liberal interest groups.

“You’re going to see Democrats lining up to run in 2013, and they’ll start next week,” said George Arzt, a longtime campaign consultant who generally works for Democrats. “For a mayor who is very confident in himself, this is an earthquake.”

The mayor often seems most comfortable working leader to leader, cultivating black ministers, community board leaders and the like. He communicates with the broader public largely from an arm’s length  with expensive television campaigns, handsome Web sites and the 311 community-service system. What perhaps was missing all along, and what will be his challenge now, is to find a more tactile, emotional connection with New Yorkers.