August 1, 2008 -- As celebrity ties go, Britney Spears and Paris Hilton don't rank high on your typical presidential nominee's must-have list.
We can assume then that Sen. John McCain knew what he was doing when, in a recent ad, he attempted to associate Democratic contender Sen. Barack Obama, the oft-described "rock star" of the 2008 campaign, with two women who made stepping out of a car without any underwear a national obsession.
"He's the biggest celebrity in the world," the ad's narrator intones as the screen cuts from pictures of Obama addressing a crowd in Berlin to images of Hilton and Spears. "But, is he ready to lead?"
Spears and Hilton did not actively, or even passively, endorse Obama -- it remains unknown if they even know who he is -- but McCain nevertheless drew a line connecting the poster girls for celebrity fluff to a politician who has also found his way onto the cover of the celebrity magazine Us Weekly and the entertainment program "Extra."
"It wasn't exactly a coincidence that McCain chose those particular women for that ad," said Kelli Lammie, a communications professor at the State University of New York at Albany, who studies the impact of celebrity endorsements on candidates.
"McCain is trying to make a connection there. Would you want either of them running the country? Of course not," she said. "He is trying to say Hilton and Spears are just fluff and so is Obama. He might be great at waving to cameras, but that doesn't mean he knows anything about foreign policy."
Beyond simply comparing Obama with the lightweight celebrities, some have seen the ads as racially tinged, said Albert May, a professor of media and public affairs at George Washington University.
Celebrities sometimes bring a candidate much-needed attention. Oprah Winfrey helped draw 30,000 people to an Obama rally in South Carolina in December, and former Gov. Mike Huckabee, R- Ark., made his endorsement by Chuck Norris a cornerstone of his ad campaign.
"My plan to secure the border? Two words," Huckabee joked in an ad early on in the Republican primary. "Chuck Norris."
Another reason to keep celebrities around? Money.
In the primaries, Barbara Streisand gave $2,300 each to Democrats Sen. Hillary Clinton, former Sen. John Edwards and Obama. George Clooney also wrote a $2,300 check to Obama.
McCain got that same amount from both Hollywood producer Jerry Bruckheimer and "Saturday Night Live" skipper Lorne Michaels.
But not all celebrities are created equal, and while you can't hold a candidate responsible for every crackpot, crackhead, miscreant or moron who pins a button to his lapel, Americans are paying attention. And there are some stars and socialites the candidates would prefer to have nothing to do with.
Hilton and Spears may not have endorsed Obama, but there are plenty of less than stellar stars who have endorsed both candidates.
Music producer Phil Spector, who pioneered the recording technique known as the Wall of Sound and made records with the Beach Boys and the Beatles, was seen recently wearing an Obama button -- at his murder trial.
At a Los Angeles court this week, Spector showed up to a hearing wearing a "Barack Obama Rocks" pin. Spector is slated to be tried for second-degree murder in the death of actress Lana Clarkson, who was found dead following a date five years ago.
Rappers Jay-Z and Ludacris are more contemporary musicians who have publicly endorsed Obama, despite sharing opinions in their lyrics about women that the candidate does not quite agree with.
Both rappers have given props to the Illinois senator in songs, but it is unlikely Obama will be blasting them on the campaign trail.
"You never should've doubted him/ With a slot in the president's iPod Obama shattered 'em/ Said I handled his biz and I'm one of his favorite rappers," Ludacris sings in "Politics: Obama is Here," adding, "Hillary hated on you, so that b---- is irrelevant."
Jay-Z and Ludacris are "great talents and great businessmen," Obama told Rolling Stone magazine. "It would be nice if I could have my daughters listen to their music without me worrying they were getting bad images of themselves."
In October, Obama took flak for including gospel singer Donnie McClurkin on a tour of South Carolina because the singer had professed antigay views.
Surprisingly perhaps, Obama isn't the only candidate to be endorsed by a controversial rapper. Young Jeezy, an Atlanta-based rapper that Vibe magazine called the "gangsta rapper of the moment," told the magazine he would be supporting John McCain after a chance meeting backstage at "Saturday Night Live."
"No disrespect to my man Barack," Jeezy told Vibe. "But I [expletive deleted] with John McCain."
McCain, he said, "greeted me like a G," meaning gangster.
"Do celebrity endorsements help or do associations hurt?" asked May. "Not much.
"You have to make a real distinction," he added, "between an endorsement that a candidate embraces, or just rap star or even a guy like [Louis] Farrakhan saying something independently."
According to SUNY's Lammie, even an official celebrity endorsement can do more harm than good.
"My work has been on celebrities invited by campaigns in one way or another," she said. "When campaigns invite celebrities, there is a bit of a boomerang effect. Voters look at Oprah or Barbara Streisand and see their involvement as a cheap trick, a stunt to get attention.
"They might look less favorably on the candidate," she said, "but more often they look less favorably on the celebrity."
No one is going to hold it against McCain that Heidi Montag, the ditzy star of MTV's reality show "The Hills," endorsed the Arizona Republican, said Lammie.
"The backlash is against her," she said. "Who cares about her political opinion? People have definite ideas about who should be voicing political views and who shouldn't, and they react poorly when celebrities talk about issues they know nothing about.
"It is one thing when Angelina Jolie or George Clooney talks about nonpartisan issues like poverty in Africa," she added, "but generally people don't care about celebrities' opinions and can get offended when they become too partisan."