In the primary on September 15, Mr. Gioia finished a disappointing third, pulling only 18 percent of the vote and lagging 12 points behind second-place finisher Mark Green.

At this time last year, the public advocate's race was expected to be another rung in Mr. Gioia's rapid ascent. He was (and still is) young, energetic, idealistic and also quite politic. He seemed to like the cameras and the cameras seemed to like him. From a citywide perch, the thinking went, he could position himself for mayor, or Congress, or whatever opportunity might come along.

And then came term limits. When the Council voted--over Mr. Gioia's objection--not to re-shuffle the political deck in 2009, the public advocate equation changed. (The two-term incumbent, Betsy Gotbaum, declined to run again.)

Shortly after the vote, another popular councilman, Bill de Blasio, declared for the seat. Before the term limits vote, Mr. de Blasio had planned to run for Brooklyn borough president, but he had re-directed his ambitions when Marty Markowitz opted to run for a third term.

And then Mark Green, a two-term public advocate in the 1990s who had sworn off politics in 2006, couldn't help himself.

Mr. de Blasio got most of the unions and the helpful Working Families Party; Mr. Green had enviable name recognition forged through his prior service in the office, and his television punditry, and a series of high-profile losses in races for other, more powerful offices. Suddenly, Eric Gioia was swamped.

Mr. de Blasio got 32 percent; Mr. Green got 30 and the two headed for Tuesday's run-off.

Mr. Gioia came in at 18 percent, but received some small--but considerable-- consolation just before the primary: a new daughter.

His camp is coy, for now, about his future plans.

"The first priority for Councilman Gioia is to spend time with his family and get to know his daughter, Rosalee, a little bit better," said his spokesman.

Developing...