Washington - The US presidential candidates put aside the serious business of courting voters Thursday night to match wits before a well-heeled crowd that expected to be entertained, not wooed.

Dressed in a white tie and black dinner jacket, Republican John McCain, 72, insisted he had dismissed his entire team of senior advisors and replaced them with "a man named Joe the Plumber" - a reference to an Ohio man who has become Everyman in the bitter race for the White House.

Democrat Barack Obama, 47, also in white tie, joked about his partial Kenyan ancestry and his middle name Hussein that has provoked centre-right Republican suspicions that he could be foreign or even Muslim.

"Many know I got my name from my father, Barack, which is actually Swahili for 'that one,'" Barack said, jabbing at McCain's dismissive reference to him during one debate. "I got my middle name from somebody who obviously didn't think I'd ever run for president."

The audience roared with delight at the unaccustomed light- heartedness and charm of the two senators, after many had just the night before watched them parry sharp verbal swords during the final debate before the November 4 elections.

The occasion was the annual fund-raising dinner to commemorate Alfred E Smith, the 1928 Democratic nominee who was the first Catholic to run for US president from a major political party.

Cardinal Edward Egan, head of the archdiocese of New York, was the referee, sitting between the political rivals at the head table, according to broadcast footage from the event.

Grist for the senators' humour mill came from iconic campaign images - like Joe Wurzelbacher, an employee of a plumbing company outside Toledo, Ohio, who was outside on his street recently when Obama strolled through his neighbourhood.

The man rocketed to fame after video clips showed the so-called plumber - it turns out he doesn't have a licence, the New York Times reported - complaining to Obama that the Democrat's plans to raise taxes on personal incomes above 200,000 dollars would interfere with his own plans to buy a plumbing company that makes 250,000 to 280,000 dollars a year.

McCain, jumping on the theme to portray Obama as a big taxer and spender, invoked Joe the Plumber repeatedly during Wednesday's debate.

But after US media camped out at the plumber's house and started investigating, they found that Wurzelbacher earns so little that he would actually benefit from Obama's promised middle-class tax cuts.

Never mind the discrepancy, McCain joked. "Joe the Plumber recently signed a very lucrative contract with a wealthy couple to handle all the work on all seven of their houses."

McCain was referring to the hubbub over his inability to remember how many homes he and his wealthy beer-distributorship-heiress wife Cindy McCain owned.

Obama made fun of the pretentious stage decorations at his own acceptance speech in August, which filled a huge Denver, Colorado, sport stadium with his supporters - an unusual, and critics said overly ambitious, event for the relative newcomer on the national political scene.

"I was originally told that we would be able to move this outdoors to Yankee Stadium," Obama said of the white-tie affair. "Can someone tell me what happened to the Greek columns I requested?"

Obama, who could become the first black US president, confessed that he actually had not been born in a manger, but rather on Superman's planet, Krypton, "and sent here by my father - to save the planet earth."

The centre-left Democrat, who has pulled ahead in the polls as the economic crisis has worsened, said it felt like an "odd time" to be dressed up in a white tie, then forged ahead with a claim that one of McCain's advisors had conceded that "if we keep talking about the economy, McCain's gonna lose."

"So I'm gonna keep talking about the economy," he jibed, drawing another wave of laughter. (dpa)