The reception at the private Pacific Club in Newport Beach aimed to promote Orange County Republicans up for election in various races.
"I think Gov. Romney did us a real favor by pointing out that 47% of people don't pay income taxes," Giuliani told the gathering of about 40, referencing Romney's recent publicity dust-up. "If Obama has his way, that will become 51% or 52%."
Giuliani was the event's keynote speaker, who event organizer and CRP Vice Chairman Steve Baric said raised $100,000 for the CRP. Other speakers included state Board of Equalization Vice Chairwoman Michelle Steel and state Sen. Mimi Walters (R-Laguna Niguel).
While attendees said it was nice simply having a man several people referred to as "America's Mayor" in Orange County to rally the Republican base, they hoped Giuliani would talk about the economy and foreign policy.
"The point of this evening is to talk about the prospects of our party," Baric said, "and to draw a clear distinction between the type of leadership [Giuliani] showed during 9/11 and the failures of the current leadership."
Giuliani heavily criticized Obama's handling of the economy, arguing that more money in the private sector, not higher taxes, will lead to recovery.
"The best government stimulus is a tax cut," he said. "This is America. [Obama] would like to see us more like France."
Giuliani also had harsh words for the Obama administration's handling of the recent attacks in Libya.
"An ambassador and three other Americans can be slaughtered on Sept. 11 and they won't figure out it's a terrorist attack," he said. "Our ambassador to the [United Nations] said it was a 'spontaneous attack.'" Members of the crowd laughed.
On Thursday, the White House described the assault as a terrorist attack for the first time.
Romney, Giuliani said, was right to "criticize the apologizing," adding that official condemnation of an inflammatory YouTube video that sparked anti-American protests in Libya and other places was equivalent to apologizing for free speech.
"Is anyone apologizing for 'The Book of Mormon,' which is on Broadway?" he asked. "It wasn't the government that mocked Muhammed. We can't apologize for every crazy, stupid moron. We'd be apologizing every day."
Giuliani next addressed the killing of Osama bin Laden. He said his death was a good thing, but that Obama has taken too much credit.
As he wound down his speech, Giuliani did give the president credit for at least one thing: "He's comfortable with himself."
"Here's my advice to Mitt Romney," Giuliani said. "Be yourself."