Meanwhile, in Kailua, the race between the two Republican primary candidates was even closer, with state Sen. Bob Hogue defeating former state Rep. Quentin Kawananakoa by a slim lead.

Hirono's slim victory came from a crowded field with several recognizable candidates, including Hanabusa and the third-leading vote-getter, Matt Matsunaga.

Of the others, only state Rep. Brian Schatz would not be returning to an elected post, since he chose to run for U.S. House rather than for re-election to the state House.

Rep. Ed Case's announcement that he would not seek re-election to the U.S. House presented an opportunity for a number of candidates who might not have challenged an incumbent but were more than willing to take a chance at an empty seat.

Five Democrats ran from "safe" seats they did not have to resign from to seek federal office: Hanabusa, City Councilman Nestor Garcia, state Sen. Clayton Hee, state Sen. Gary Hooser and state Sen. Ron Menor will return to their offices at the state Capitol or City Hall.

Similarly, businessman Hanalei Aipoalani and attorney Joe Zuiker were first-time candidates with nothing to lose and only statewide recognition to gain.

For Hirono and former state Sen. Matt Matsunaga, the open seat offered hope of returning to elected office after they were beaten by Gov. Linda Lingle and Lt. Gov. James "Duke" Aiona in the previous election.

The campaign also heralded a return to politics for Kawananakoa, one of two Republicans in that primary.

The other Republican, Hogue, like Schatz, decided to run for Congress rather than run for re-election for his state seat.

Earlier in the evening, the leading candidates seemed optimistic but wanted to see more vote totals before claiming victory or conceding defeat.

"It's going in the right direction, but we definitely can't predict anything," Hirono said at about 8:40 p.m. "We're waiting for the second printout."

The mood at the International Union of Painters and Allied Trades, where Hirono's supporters gathered, was positive. "Everybody's very happy," she said.

At Hanabusa's headquarters at Fort Street Mall, the mood was similarly upbeat, for although the senator trailed, the first printout showed her leading on O'ahu.

"I guess the question is the Neighbor Island votes coming in," she said. "I think this is going to be a long evening all the way to the end."

Kawananakoa was similarly prepared for a long night. "It's very close," he said after the first printout, which showed him trailing Hogue by only 500 votes in the Republican primary.

By the second printout, the difference was only 400 votes.

A few blocks away, Hogue had a large crowd of his own to keep him company as the results came in.

"We're very optimistic and we're very pleased," he said. "We've got a big crowd here, and they're very enthusiastic."

Despite the prestige of the seat and the caliber of the candidates, the campaign generated little buzz as the Democrats ran collegial campaigns that made it difficult for any clear front-runner to emerge.

Throughout the campaign, observers speculated that the candidate with the greatest name recognition would win by a slim margin, a prediction that came true as the results rolled in.

The district covers the entire state, save urban O'ahu, and the most outlying precincts are traditionally the latest to file.