US President Barack Obama said on Thursday that gay marriage is a "logical" milestone toward a more equal America, as he was feted at a Hollywood fundraiser tipped to make a cool $15 million.

In a Tinseltown love-in at George Clooney's Hollywood Hills home, the US president praised his host's support for liberal causes but also gently teased the A-list actor and Democrat supporter.

"Yesterday, we made some news," he joked about his public endorsement of gay marriage on Wednesday. "The truth is, it was a logical extension of what America's supposed to be ... Are we a country that includes everybody?"

"Does that make us stronger? I believe it does," he said to applause at the dinner in a party tent on Clooney's basketball court, beneath the trees of the wooded hillside property.

Dubbed "Starmageddon", the event at the Oscar-winning star's mansion, which united Hollywood glitz and Washington power, was aimed at swelling Obama's campaign coffers six months before he asks voters for a second term.

Around 150 well-heeled guests paid $40,000 a ticket to get into the exclusive soiree, the latest in a string of big money events as Obama builds an expensive campaign machine for his re-election and buys top dollar advertising slots.

The Obama campaign also conducted a draw for tickets, asking less wealthy supporters for contributions of at least $3 for a chance to chow down with the star of Ocean's Eleven and the US leader.

DreamWorks Animation chief Jeffrey Katzenberg, who organized the fundraiser, introduced Obama after remarks by Clooney and recalled Obama's 2008 campaign slogan: "Yes we can".

He continued: "Yes, we have. Yesterday, he did the right thing yet again" - sparking renewed cheers. Katzenberg was also overhead saying the fundraiser was set to make "close" to $15 million, an AFP reporter at the scene said.

Obama paid tribute to Clooney in remarks at the start of the evening, saying: "We raised a lot of money because everybody loves George. They like me, they love him. And rightfully so."

Referring to the iconic "Hope" poster from 2008 by Shepard Fairey, he said: "People don't realize that the photograph of me is actually me sitting next to George", who was advocating on behalf of Darfur.

"We struck up a friendship. This is the first time that George Clooney has actually been photoshopped out of a picture," he quipped.

In fact, Fairey did a poster for Clooney with both men on the same picture, Obama revealed. "Why he said at the bottom, 'Dope and Hope', I don't know", he joked.

The guest list included A-listers from Barbra Streisand and Robert Downey Jr to Jack Black, Billy Crystal and Salma Hayek, and fashion designer Diane Von Furstenberg.

Obama's decision to publicly endorse gay marriage has electrified his liberal base and restored some of the transformative luster that had dimmed since his 2008 campaign.

"Pretty darn happy today. Thanks Mr President, for supporting the dignity of my family and so many others!" said actress Jane Lynch of the hit TV series Glee on her Twitter feed.

Hollywood is a traditional source of funding and adulation for Democratic presidents, though there have been persistent reports that Tinseltown feels it has not been feeling sufficient love from Obama.

Many in California remember the attention that former president Bill Clinton lavished on them. Hollywood was also a prime source of funding for Clinton's wife Hillary when she ran against Obama for the Democratic nomination in 2008.

Republicans seized on Obama's evening rubbing shoulders with the stars to claim that the "Celebrity in Chief" was out of touch with ordinary Americans.

"With middle-class Americans reeling from the effects of Obama's failed leadership, not even Hollywood magic can cover up the truth," said Republican National Committee Chairman Reince Priebus on the blog Red State.

"With a first term this disastrous, we can't afford to see the second - because if we've learned anything from Hollywood, it's that the sequel is always worse."

Agence France-Presse