In this crowd, Obama didn’t even need to mention gay marriage to get a vigorous applause. “Obviously,” the president said obliquely, “yesterday we made some news.”

The event, held under a stretched transparent tent outside Clooney’s sprawling tudor-styled canyon home, raised nearly $15 million, a record for a single fundraiser.

The guests paid $40,000 to attend, accounting for about $6 million of the evening’s financial haul for Obama’s campaign and the Democratic Party. The remainder came from a raffle for small dollar donors. Two winners — both women — got to take part in the dinner and, even though Clooney was the host, they brought their husbands.

“We raised a lot of money because people love George,” Obama said. “They like me; they love George.”

Then seriously, he added: “He seems to occupy a constant state of grace, and uses his extraordinary talents on behalf of something truly important.”

For Obama, the A-list party was not only a financial hit, it gave the president the kind of Hollywood buzz a Republican seldom gets. But the glitzy event, with its glamour and wealth, also has its risks and it set up a stark contrast with Obama’s mission on Friday to highlight the plight of struggling homeowners in Nevada.

Among those at the dinner were such actors and performers as Robert Downey Jr., Barbra Streisand and her husband James Brolin, Jack Black, Salma Hayek and Tobey Maguire, who shared a table with Clooney and Clooney’s girlfriend Stacey Kiebler.

Heading to Clooney’s house, along the exclusive canyon roads, families gathered at dinner time to gawk, wave and cheer the presidential motorcade. Children manned a lemonade stand with a sign: “Presidents drink free.”

Around the corner, a boy held up another hand-drawn piece of cardboard: “Will trade Lakers for Bulls if you stop.”

And yet one more: “Our gay family says thanks Mr. President.”

“Smart rules can save lives and keep us safe, but there are some regulations that don’t make sense and cost too much,” Obama said in remarks prepared for the announcement. “We will remain vigilant when it comes to eliminating regulations that are not necessary or that impose unnecessary burdens on America’s families and businesses.”

As a step in that effort, the White House is announcing the repeal of five rules that it says will save local governments, health care providers, railroads and gas stations a total of $6 billion between now and 2017. Last year, the White House identified several other rules for elimination.

The savings identified by the administration benefit the institutions and industries affected by the regulations. They do not represent savings in government spending.

Administration officials said they expected the changes and Obama’s executive order mandating regular reviews to hearten the business community, which has complained that the federal government has put an undue burden on them through regulations.

The changes so far, however, are small compared to what business groups like the U.S, Chamber of Commerce are demanding, especially in environmental requirements and workplace rules.

Obama called for federal agencies to conduct a one-time review of their existing regulations early last year after his party suffered sweeping losses in the 2010 elections. At the time Obama conceded that his relationship with the business community had soured, and he vowed to scrap “dumb” rules that were hindering private sector growth.

The president’s Council of Economic Advisers, in a report Thursday, says agencies already have identified more than 500 possible changes. The executive order Obama will sign Thursday will make those reviews a regular and recurring function of federal agencies.

Among the five finalized rule changes that are to be announced Thursday, some of the biggest saving come in changes that do away with unnecessary reporting requirements by hospitals that treat Medicare and Medicaid patients.

Another change would put off a requirement on state and local governments to design more uniform street and traffic control signs. Administration officials said many local governments complained that the requirement could them precious money at a time of tight budgets. The officials spoke on the condition of anonymity to describe the initiative ahead of the announcement.

In one change that might be familiar to many car owners, the Environmental Protection Agency is eliminating a mandate that some states require vapor control devices on gas nozzles at gasoline stations. The officials said the rule was set in 1990 before many vehicles required built-in pollution controls.

Overall, the dinner is expected to raise close to $15 million — about $6 million from the guests and the rest from a campaign contest for small-dollar donors, the winners of which get to participate in the dinner. It is an unprecedented amount for a single event. And it means that in one single evening the Obama camp and the Democratic Party will collect more than Mitt Romney, the presumed Republican challenger, has amassed in his best single month of fundraising.

Obama will also hold fundraisers earlier in the day in Seattle, where he was expected to collect at least $3 million toward his re-election effort. On Friday, he will fly to Nevada, a highly contested state, where he will call for housing relief in a speech in Reno.

But Obama’s support of gay marriage, announced in an ABC interview Wednesday, will be dominant, culminating in yet another fundraiser Monday in New York sponsored by gay and Latino Obama supporters.

“I have hesitated on gay marriage in part because I thought that civil unions would be sufficient,” Obama said in the interview. But he added that now, “it is important for me personally to go ahead and affirm that same-sex couples should be able to get married.”

Even though Obama doesn’t have the power to make same-sex marriage legal, his announcement was the first by a sitting president. Gay rights advocates, who had long urged Obama to state his support, immediately cheered his declaration. By day’s end Wednesday, the Obama campaign had emailed a clip of the interview and a personal statement from the president to its vast list of supporters, drawing attention to his stance.

As much as his announcement may energize his core backers, however, gay marriage remains enough of a divisive issue that there could be political risks. If opposition to gay marriage drives even a sliver of the voting population, it could make a difference in close swing states. Moreover, it could boost fundraising for social conservative groups that are mounting their own campaigns against Obama and galvanize conservatives still uncertain about Romney’s commitment to their causes.

“Twenty-four hours ago, we were talking about what Romney had to do to get social conservatives on board,” said Ralph Reed, chairman of the conservative Faith & Freedom Coalition. “Now, they’re scrambling for a seat in first class.”

Romney, meanwhile, quickly reiterated his opposition to same-sex marriage. “I believe that marriage is between a man and a woman,” he said while campaigning in Oklahoma.

In announcing a position that he said had been evolving for some time, Obama emphasized that it was his personal view. Aides said he continues to believe that marriage is an issue best decided by states.

His decision came just a day after voters in North Carolina, a state the Obama camp hopes to be in play in November, approved an amendment to the state constitution affirming that marriage may only be a union of a man and a woman. It also came just days after Vice President Joe Biden unexpectedly ignited a discussion of the issue by declaring he was comfortable with same-sex marriage.

In some ways, Obama is a lagging voice among Democrats on gay marriage. Besides Biden, former President Bill Clinton has expressed support and Obama’s education secretary, Arne Duncan, said Monday that he backed gay marriage as well. In addition, former Vice President Dick Cheney and New York Mayor Michael Bloomberg have taken stands in support.

“It was probably untenable to keep in a position of evolving and not stating where he is, given the course of events,” said Anna Greenberg, a Democratic pollster who has conducted a number of surveys on gay marriage.

With his position declared, Obama now heads to Hollywood, which has been outspoken in its support of gay rights. But though Obama will be in a liberal bastion, California itself illustrates the crosscurrents of gay marriage. Californians have twice voted to ban gay marriage, most recently in 2008. The most recent ban, known as Proposition 8, is being fought in the courts.

Clooney’s dinner was organized by Jeffrey Katzenberg, the CEO of DreamWorks Animation, and will include such celebrity guests as Robert Downey Jr. and Barbra Streisand. The event was initially to be a spring gala hosted by Katzenberg at his house. But Katzenberg’s home is under renovation, so Clooney offered to host instead.

That prompted the Obama campaign to conceive an online raffle for the general public. Tens of thousands of people participated, drawn by the campaign’s pitch: “For a chance to hang out with President Obama at George Clooney’s house, donate $3 or whatever you can to be automatically entered to win.”

As a result, nearly two-thirds of the money raised for the event will be from people who won’t attend. The two winners are each allowed a guest. Their names will be announced Thursday night.

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Associated Press writers Julie Pace and Laurie Kellman contributed to this report.