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."