The reach of MySpace and YouTube now extends to the White House: Social network sites are reshaping how candidates run campaigns, said experts at a recent conference on social networking, hosted by the George Washington University Institute for Politics, Democracy & the Internet.

MySpace, blogs, YouTube and other social-networking sites are making the controlled, broadcast-style way of distributing political information obsolete, says Henry Copeland, president and founder of Blogads, an advertising service for blogs. “The people we’re dealing with today are no longer ‘consumers,’ they’re participants.”

Politicians who ignore the impact of blogs and other social-networking sites miss a huge number of potential voters, says Tom Gerace, founder and CEO of Gather.com.

MySpace, which boasts 108 million member profiles, has more than 7,400 discussion groups related to politics, plus pages created by or for candidates like Arizona Republican John McCain and Nevada Democrat Wesley Clark.

Of course, MySpace also has user groups devoted to the legalization of marijuana and the claim that Republicans are better in bed. This kind of content makes some people question whether social networking’s growing influence on campaigns is such a good thing.

“It’s healthy for democracy for more voices to be heard,” says Chuck DeFeo, general manager of Townhall.com. “People get more involved in politics.”

Politicians also face a new reality due to the rise of social networking and blogging: “Citizen journalists” armed with video cameras or a blog platform can show up anywhere.