President Obama's announcement of his support for gay marriage Wednesday was greeted with enthusiasm in San Francisco’s Castro District as locals geared to celebrate the momentous day.

Mr. Obama is the first sitting president in history to come out in support of gay marriage.

It was such an important milestone that California's Lt. Governor Gavin Newsom and Assembly Speaker John Perez appeared on the steps of San Francisco’s City Hall Wednesday to discuss the announcement.

"For me, this is a statement of leadership and a statement of character," said Newsom. "And for those that may disagree with the president on this, I hope they'll respect and reflect on the fact that rarely do you see this kind of presidential leadership."

Of course, San Francisco is where the fight for marriage equality kicked into high gear in 2004 when then new Mayor Gavin Newsom allowed thousands of same sex couples to tie the knot.

"What we did right here on the steps of City Hall -- remarkably eight years ago; it doesn't feel as though it was that long ago -- was put a human face on the issue," said Newsom.

And since then, there has been a dramatic shift in public opinion polls, with a majority of Americans now supporting same-sex marriage.

If Newsom's experience is any guide, Obama also stands to reap some rewards for his historic stand, the lieutenant governor and gay political leaders in California said.

Among the benefits are loyalty from many Hollywood donors and gay, lesbian and young voters — constituents who are now likely to support Obama's reelection bid with renewed enthusiasm.

"I have a sense of optimism and gratitude and personal gratification that he's willing to put his entire political career on the line in this way," Newsom said. "Overwhelmingly those who have the courage to stand up on this issue have survived."

Gay marriages remain illegal in California while the fate of Proposition 8, the constitutional amendment that outlawed same-sex unions in 2008, remains tied up in the courts. The most recent Field Poll of registered voters, published in February, found that 59 percent endorse gay marriage rights. When Proposition 8 passed in November 2008, the figure stood at 49 percent.

Perez, who is the state's first openly gay speaker, also issued a statement saying he was "proud of the President."

"The fact that the president really came out at this point sends a powerful message across the country about the fundamental belief in equality," said Perez.

Shortly after President Obama's announcement, several state legislators in Sacramento praised it.

State Senate President Darrell Steinberg issued a similar statement.

People in the Castro were thrilled to hear the President's words. Many told KTVU they are optimistic about marriage equality going forward.

"I think it's amazing that he has expressed any thought on it," said San Francisco resident Steve Payne. "So, yeah, it's great that he's in support."

"We're constantly evolving and progressing. Back in the 1930s and 40s, nobody would have guessed that African-Americans would have all the rights that they have," said San Francisco’s Carly Frisbie. "You know, there's steps that have to be taken every single day."

Fred Karger, a gay Southern California resident who is running as a Republican candidate for president this year and will appear on the June 5 GOP primary ballot with Mitt Romney, half-jokingly said in a message to his supporters Wednesday that, "It's nice to have another presidential candidate on board for full equality."

On a more serious note, Karger said in an interview that Obama's evolution would disarm gay marriage opponents of a powerful rhetorical weapon. In 2008, Proposition 8's backers used a snippet of Obama explaining his opposition to same-sex marriage rights in a robo-call to California voters, and have continued citing the president's now-relinquished view to maintain they speak for the mainstream.

"Now, Republicans and Democrats cannot use that line," Karger said.

Obama is scheduled to be in California twice for fundraisers during the next month, one at the home of actor George Clooney on Thursday night and another aimed specifically at gay donors on June 6.

Movie producer Bruce Cohen, a founding board member of the group funding the court fight to overturn Proposition 8, predicted that the president's new position will have a huge effect on his reception at the events.

"Up to this point, I've had moderate success raising funds for the June 6 event. After this point, I expect to have a lot more success," Cohen said. "I'm excited to go out to everyone again, because now there is no, 'Please, just hold on and grin and bear it.' There is no apology needed in the plea for his reelection."

Chloe Harris Frankeny, a San Francisco magazine editor who married her wife, Frankie, in the weeks before Proposition 8's passage, said the couple always knew Obama would eventually support same-sex marriages but "kind of suspected he would lame duck it" and wait until after November. Frankeny now feels like she has a lot to hope for.

"When he spoke today, I thought, OK, I'm in. I will donate now," she said. "There was never any doubt I would vote for him in this election, but now I feel compelled to support him in a way I might not have before."

Newsom said Obama showed courage taking the position so close to an election but added the president had been in an untenable position because the longer he avoided the gay marriage issue, the more he alienated his base.

"The brand was being impacted, the president's brand of being an authentic leader, of not reading the polls but changing the polls," Newsom said.

The San Francisco Lesbian Gay Bisexual Transgender Community Center at 1800 Market St. threw a party at the center with champagne and speakers including local activists and same-sex couples who have been involved in the fight for marriage.

The center's executive director Rebecca Rolfe acknowledged "we are really lucky to be here in San Francisco where there is widespread support for the LGBT community," and now "there's a groundswell of support" across the country.

Across the Bay Area and beyond, government officials have issued statements in response to the president's historic announcement.

San Francisco Mayor Ed Lee, who was appointed as interim mayor by former Mayor Newsom before Lee won the post in the November 2011 election, said in a statement that in San Francisco "we stand ready to begin marrying same sex couples, and we will take this hard fought fight all the way to the nation's highest court, if necessary."

City Attorney Dennis Herrera who has fought on the legal front of gay marriage said he was "delighted" with the president's announcement.

"President Obama now stands with San Francisco on the right side of history," Herrera said in a statement.

Herrera has worked to federally challenge Proposition 8, which was passed into California law in 2008 and eliminated the rights of same-sex couples hoping to marry.