It is too soon to tell whether President Obama’s endorsement of same-sex marriage will help him or hurt him at the polls in November. But it’s already doing wonders for his campaign’s pocketbook.

Obama’s reelection team is experiencing a major surge in contributions since his announcement, suggesting that the issue could serve as a powerful fundraising tool in the months ahead, according to campaign bundlers and donors.

Fundraisers say the donations began pouring in within minutes of the news Wednesday that Obama, who said he had been “evolving on the issue” for months, affirmed his support for the right of same-sex couples to be married.

The Obama campaign and Democratic Party committees have begun to focus on the issue in their fundraising appeals.

“I am just so happy,” read one fundraising message sent Thursday by Obama finance director Rufus Gifford, who is gay. “If you’re proud of our president, this is a great time to make a donation to the campaign.”

The issue also could benefit the fundraising efforts of presumptive Republican nominee Mitt Romney, who sides with social conservatives in favoring a constitutional amendment banning same-sex marriage.

But Romney said in an interview Thursday that he would not attempt to raise money on an “issue as tender” as the definition of marriage. “I don’t think the matter of marriage is really a fundraising matter either for the president and it certainly is not for me,” he told Fox News Channel.

Obama campaign officials declined to say how much money has come in since Wednesday, but one source involved in the effort called the response “astounding.” A spokesman discounted reports that $1 million was donated in the 90 minutes after the president’s announcement.

Regardless of the specifics, it’s clear that Obama’s shift on same-sex marriage is reaping financial rewards for his reelection campaign. The lesbian, gay, bisexual and transgender community forms an important constituency for him, and gay rights issues animate a broad part of the liberal base regardless of sexual identity.

His position on same-sex marriage could also boost fundraising efforts by independent liberal groups, which have struggled to match better-funded conservative groups. Bill Burton, a spokesman for Priorities USA Action, a pro-Obama super PAC, said the president’s announcement “will almost certainly increase enthusiasm from progressives across the spectrum, both gay and straight.”

An increase in contributions from young and progressive donors could be particularly important for Obama as he struggles to match his performance four years ago, when a hard-fought primary contest and an idealistic wave of supporters helped him shatter campaign finance records.

Fundraisers said many donors have chosen to max out their contributions to the campaign and the Democratic Party over the past day as a sign of support for the president’s stance. Donors this year can give $5,000 to Obama and $30,800 to the Democratic National Committee, as well as additional amounts to committees formed to help Obama in swing states.

“Here I thought the LGBT community was already knocking it out of the ballpark for Obama, and now I see they’ve expanded the ballpark,” said Andrew Tobias, a longtime gay rights activist and treasurer of the DNC. “And many of my straight donors are energized as well. People are excited up and down the line.”

Jonathan Lewis, a major gay fundraiser who had vowed not to back Obama’s reelection effort, is now doing just that and has contributed the maximum amount possible to the campaign, according to a report by The Washington Post’s Plum Line blog.

The announcement on same-sex marriage comes at a time of frenetic fundraising by Obama and Romney, who hosted a gathering in Nebraska on Thursday that reportedly brought in $800,000.

On Thursday night, Obama was slated to attend a $40,000-a-plate dinner at the Los Angeles home of actor George Clooney that could net as much as $16 million in donations online and in person, top donors said.

The campaign has called that number too high but has declined to provide further details. The event could turn out to be the most profitable presidential fundraiser since unlimited donations to political parties were banned a decade ago.

The president is scheduled to return to Los Angeles on June 6 for an LGBT gala to be attended by up to 700 people. Lawyer Dana Perlman, who is helping to organize the event, said he was “ecstatic” about Obama’s endorsement of same-sex marriage and says he expects gay men and lesbians to respond with contributions.

“This man has come out 100 percent for our community, and each and every member of the community must now step up and do everything he or she can to see that he is reelected,” Perlman said.

Staff writer Scott Wilson contributed to this report.