WASHINGTON — Rep. Mazie Hirono of Hawai'i, a Democratic superdelegate, yesterday announced she will support Barack Obama for president at the party's national convention in Denver on Aug. 25-26.

By picking up the backing yesterday of nine superdelegates, including Hirono, Obama all but erased Hillary Rodham Clinton's once-imposing lead among national convention superdelegates.

Clinton has 272.5 superdelegates to Obama's 271. A little more than four months ago, on the eve of the primary season, she held a lead of 169-63.

Hirono said she decided to support Obama, an Illinois senator with Hawai'i roots, "after watching these historic (primary) campaigns unfold" across the country.

"It is clear that Americans want our country back on a course of hope and opportunity," said Hirono, who had been uncommitted until now.

Hirono said she made her announcement "with deep respect and admiration" for Clinton.

"She is an extraordinary woman," Hirono said. "However, it is time to unite the party behind Senator Obama and to use our energy and resources to defeat (presumptive Republican nominee) Senator John McCain."

Hirono also said she was proud of Obama's deep roots in the state and of the way the state's Democrats embraced his candidacy in the February caucuses. Obama took 14 of the 20 regular delegates in the caucuses while Clinton won 6.

"His love for Hawai'i and understanding of its diversity have given him a foundation for understanding the diversity of our country," she said.

With Hirono's commitment, only Sen. Daniel Akaka, D-Hawai'i, remains in the uncommitted superdelegate column among the state's congressional delegation.

Rep. Neil Abercrombie was an early Obama supporter and has campaigned for him in a number of states. Sen. Daniel K. Inouye committed early to Hillary Rodham Clinton.

Among the state's remaining five superdelegates, only DNC committeeman Richard Port has committed so far, and he backs Clinton.

Three will not be chosen until the state party convention later this month and DNC committeewoman Dolly Strazer remains uncommitted.

It is highly unlikely that either Obama or Clinton can win enough of the remaining delegates to gain the nomination without the help of superdelegates — members of Congress and other party leaders whose support is not tied to the primary or caucus results. A candidate needs 2,025 delegates to win the nomination at the party convention in Denver this summer.