President Obama’s announcement Wednesday that he supports same-sex marriage highlights the importance of the gay community to his re-election effort, which could get a boost in donations as a result.

Many of Obama’s key financial supporters are gay--including finance director Rufus Gifford and Democratic National Committee treasurer Andrew Tobias--and the campaign has regularly held fundraisers focused on lesbian, gay, bisexual and transgender donors.

A review of Obama’s top bundlers, who have brought in $500,000 or more for the campaign, shows that about one in six publicly identify themselves as gay. His overall list of bundlers also includes a number of gay couples who have wed in jurisdictions where same-sex marriage was legal.

“It’s a very important constituency,” said Los Angeles attorney Dana Perlman, a top Obama bundler who is helping organize a 700-person LGBT fundraiser for the president on June 6. “The community for the most part is wholeheartedly behind this man.”

But that relationship was put to the test this week after Vice President Joe Biden said he was “absolutely comfortable” with same-sex unions. The remarks led to mounting pressure on Obama to also shift his position on gay marriage, which he had previously characterized as “evolving.”

“I’ve just concluded that for me personally it is important for me to go ahead and affirm that I think same sex couples should be able to get married,” Obama told ABC News Wednesday.

Some liberal gay donors had threatened to withhold contributions over Obama’s stance on gay marriage as well as his administration’s decision to shelve an executive order banning sexual-identity discrimination by federal contractors.

Likely Republican challenger Mitt Romney favors a constitutional amendment defining marriage as between a man and a woman, and does not appear to have an outreach effort aimed at LGBT voters. Romney reiterated his opposition Wednesday, a stance that could help him raise money from social conservatives strongly opposed to gay marriage.

The Obama campaign’s list of bundlers includes a number of prominent names in the gay community. Rainmakers at the top $500,000-and-up level include Perlman; interior designer Michael S. Smith and HBO executive James Costos; Chicago Cubs co-owner Laura Ricketts, a board member of the Lambda Legal gay rights group; and Colorado political activist Tim Gill and his husband, Scott Miller.

The Advocate, a publication focused on the gay community, assembled a list of “Obama’s Power Gays” last year that included many of his biggest fundraisers. In addition to Perlman and others, the Advocate list included Pfizer executive Sally Susman ($500,000-plus); activist Kevin Jennings ($50,000 to $100,000); and Texas philanthropist Eugene Sepulveda ($500,000-plus).

Chad Griffin, the incoming president of the Human Rights Campaign, which has at times criticized Obama’s stance on gay issues, has raised between $100,00 to $200,000 for the president’s re-election campaign.

Griffin was the person who asked Biden at a recent closed meeting with gay activists, “How do you feel about us?” Biden recounted the question, and his emotional answer supportive of gay marriage, during his interview on NBC’s “Meet the Press.”

Griffin said in an interview with the Washington Post earlier this week that he had repeatedly pressed Obama in private to support marriage equality.

Prior to his decision to come out in favor of gay marriage, many of Obama’s strongest supporters in the LGBT community said he deserved breathing room given his succeess in allowing gays in the military and on other issues. Many of Obama’s top donors and advisers are particularly worried about the impact that the issue could have in swing states such as North Carolina, where voters overwhelmingly approved a constitutional ban of gay marriage on Tuesday.

Ray Mulliner, philanthropic and political adviser to former Luxembourg ambassador James C. Hormel, a prominent donor in the gay community, said last week that many of Obama’s supporters accept that he needs some flexibility.

“We can only assume, given his educational background and former comments in support of this issue, that he will in fact be more supportive after the election,” Mulliner said at the time. “I think that we are sophisticated enough to realize that in an election year we can only expect so much from the president.”