Celebrities, with their unique ability to connect with people, are arguably the most influential voices in American life. From George Clooney fundraisers to Bruce Springsteen concerts, celebrities are the glam and glitter of political campaigns -- bringing star power to otherwise mundane events and policy discussions. But do they matter? Can celebrity appearances, endorsements and emails move the needle? The answer: It depends. Voters don't want to think Hollywood celebrities are telling them how to vote. They understand their expertise is outside the political world," said Darrell West of the Brookings Institution. But there are exceptions. Oprah Winfrey is one. She helped launch the career of then-candidate Barack Obama in 2008, lending the largely unknown Illinois senator much-needed credibility in his race against Hillary Clinton. Also, celebrities can give a boost with certain targeted audiences. "Celebrities can help in particular niches, particularly in terms of get out the vote efforts because there you can match a celebrity and target and appeal to those types of communities," said West. A recent advertisement by actresses Eva Longoria, Scarlett Johansson and Kerry Washington, urges women to vote for President Obama because of Mitt Romney's position on Planned Parenthood. It is not directed to all women, but a young, single demographic. "People who do read a publication like US Weekly probably aren't on political websites," said Jennifer Peros of US Weekly. But when they see pictures of these celebrities in these magazines endorsing the presidential candidates, they definitely are paying attention more. America loves its celebrities. Think People magazine and "Access Hollywood." Readers know what they eat, where they shop and who they date. They buy products celebrities endorse. People paid $11 million for the photos of twins born to Brad Pitt and Angelina Jolie. It's an obsession with tinseltown's elite that is easily derided. But the campaigns know megawatt stars can deliver crowds, if not money. Proximity to stardom can reap big benefits for a politician. "It is an arms race of celebrity endorsements," said West. If the other side has some Hollywood stars, you need to have your own stars, otherwise you look weak in comparison. On this count, President Obama wins. He counts on Hollywood heavyweights like Oprah, Clooney and Tom Hanks, who narrated his convention biopic. Robert De Niro, Will Smith, Magic Johnson and Antonio Banderas help attract the big-dollar givers. A performance by Grammy-winning rock band Foo Fighters for 1,000 supporters in Los Angeles helped Obama raise more than $500,000 in February. Cee Lo Green opened another fundraiser in Atlanta at Tyler Perry Studios. Tickets ranged from $500 for general admission to $2,500 and $10,000 for VIP. Fundraisers by Clooney and singers Jay-Z and Beyonce raised more than $20 million for Obama. Romney counters with actors Clint Eastwood, Robert Duvall, Kelsey Grammer, Chuck Norris, Jon Voight, Adam Sandler, James Caan, Sylvester Stallone, Tom Selleck, Gary Sinese, Jon Cryer and 'Dirty Jobs' star Mike Rowe. In music, Romney Revolution has attracted Kelly Clarkson, Donny and Marie Osmond, Charlie Daniels, Trace Adkins, Ted Nugent, Hank Williams Jr., Gene Simmons, and Randy Owen, lead singer of the country rock band Alabama. "People look at celebrities like they're our friends," said Peros. When you see celebrities come out for political events, it definitely brings a different demo -- a different group of people into politics. It definitely brings people who probably weren't paying attention to politics and makes them interested in them. But celebrity associations and endorsements are not without risk. In 2000, Cher was caught at an Al Gore event advocating views about the Middle East at odds with the candidate. Cee Lo Green has an expletive-filled hit that translates, in the cleaned up version, to "Forget You." Samuel L. Jackson appears in an ad for President Obama titled, "Wake the f--- up!" Morgan Freeman called Tea Party activists "racists." Eva Longoria offended countless women when she re-tweeted the message: "I have no idea why any woman/minority can vote for Romney. You have to be stupid to vote for such a racist/misogynistic tw*t. On the other side, Eastwood took heat for his "empty chair" routine on the closing night of the Republican National Convention. Hank Williams Jr. last year also had to apologize after he compared Obama to Hitler. "There can be a boomerang effect from certain celebs endorsements," said West. Stupid statements can cause harm for the candidate.