On Sept. 7, somebody named "Tapperjapper" used his YouTube account to post an 11-second video clip from an ABC interview with Barack Obama that seems to have the Illinois senator admitting to "my Muslim faith." Minutes later, however, San Francisco-based Obama supporter Alex Chaffee responded with a more complete 119-second video of Obama's interview with George Stephanopoulos, in which Obama's verbal slip was part of a longer conversation about politics and religion.

Chaffee posted the counter-clip because the 11-second clip "was so blatantly out of context." He said he posted the video without any prompting from the Obama campaign, and with only a few minutes' work. "It was a lark -- I'd had too much coffee that morning," said Chaffee, who is a software consultant. As of Monday, his video had accumulated 836,621 views, significantly more than Tapperjapper's 648,642 views.

The candidates and their camps watch underground campaigns and see links, even if only tenuous, between these and the official campaign operations.

Asked for a comment, Tapperjapper declined to reveal his identity, but he said that "both sides not only use YouTube to disperse information and images to the users of YouTube, but to the media as well." He said he does not believe Obama is a Muslim, but only posted the video "to highlight this major slip."

Internet posts are "a guerilla tactic... where the little guy with total anonymity can strike back at the big guys," said Eric Dezenhall, a public relations consultant in Washington whose specialty is helping companies in crisis. With the Internet, "it is much easier to spread a flame than it is to put one out," so companies and political campaigns must work prior to a crisis to shape public opinion, he said.

"News flies around the world multiple times before you have time to address the distortions," said Chris Lehane, who has worked as a spokesman for numerous Democratic politics and causes. "One of the best antidotes is to make sure you have a candidate and a campaign that is credible, so that when you step out [to counter an Internet-amplified charge], people will believe you," said Lehane, whose clients have included Hillary Rodham Clinton, as first lady, and Michael Moore, the director of the left-of-center documentary "Fahrenheit 9/11."

After a video is posted, there's often no taking it back. CBS News experienced YouTube's permanence when a John McCain video took out of context comments said on air by anchor Katie Couric, using them to suggest Obama made sexist remarks about vice presidential candidate Sarah Palin. The clip was removed for copyright violations, but users who had already made copies reposted the video, which is still easily found by searching YouTube.

There's no way to determine if Chaffee's and Tapperjapper's videos switched a single vote, but it is clear that the candidates and their camps watch such underground campaigns and see links, even if only tenuous, between these and the official campaign operations. For example, when told by Stephanopoulos that McCain campaign manager Rick Davis had denied spreading the Muslim rumor, Obama declared that "these guys love to throw a rock and hide their hand."

McCain "hasn't suggested... that I'm a Muslim, and I think that his campaign's upper echelons have not either," Obama said. "What I think is fair to say is that coming out of the Republican camp, there have been efforts to suggest that perhaps I'm not who I say I am when it comes to my faith, something which I find deeply offensive and that has been going on for a pretty long time."

To counter such stories, Obama's team adopted new tactics. These tactics include the creation of their own Web site, fightthesmears.com; the purchase of targeted advertising on Internet search engines; and the use of their many online supporters to raise the visibility of the campaign's messages on Google and YouTube.

The targeted advertising can be seen on Google, where a search for "Is Obama a Muslim" delivered a top-of-the-page sponsored link for fightthesmears.com, whose text on the Muslim faith allegation reads, "Barack Obama is a committed Christian. He was sworn into the Senate on his family Bible. He has regularly attended church... but shameful, shadowy attackers have been lying about Barack's religion, claiming he is a Muslim instead of a committed Christian."

The site also includes sections intended to rebut other Internet-amplified criticisms, including criticisms that Obama took advice from Fannie Mae executives, opposes rights for gun owners, and opposes restrictions on late-term abortion.

The effect of the Obama campaign's huge e-mail list can also be seen on YouTube's politics page, where the two parties vie for prominence. On Oct. 10, nine of the 12 most-watched political videos that week were favorable to the Obama campaign, and only two were favorable to the McCain campaign. The Obama-favoring videos had been viewed a total of 5.5 million times, while the McCain-favoring videos had been viewed only 800,000 times. On Monday, the two sides each had four favorable videos in the top 12. The pro-McCain videos had 2.4 million views, just behind the pro-Obama videos, which had 2.5 million views. Both candidates e-mail their supporters urging them to watch campaign-produced videos in the hope they will be boosted up to the most popular rankings on the YouTube politics page.

These most-watched numbers are valuable, especially because the campaign videos cost little to produce and broadcast. But the weekly most-watched numbers are dwarfed by the numbers of YouTube's monthly most-watched Web page. Of those top 12 videos on Oct. 10, 11 with a total of 23 million page views were favorable to Obama, and only one, with 2 million views, was favorable to McCain. The most popular videos were those showing comedian Tina Fey satirizing Palin on "Saturday Night Live." By Monday, seven videos, with 15.6 million views, aided the Obama campaign, while three videos, with 8.8 million views, aided the McCain campaign.

The McCain campaign is also using the Internet to rebut charges against Palin that she improperly fired an Alaska police official. Its campaign Web site includes a "Palin Truth Files" page that tags Palin's Alaskan critics as Democratic partisans and conspirators.

Both campaigns find themselves entwined with online supporters who have no formal link to the campaign. The supporters can help by magnifying the campaign's message, but they can also embarrass and damage the campaign by launching wild accusations, such as the claim by McCain partisans that Obama is a Muslim. These Internet supporters can also nudge the campaign in new directions. For example, McCain supporters have used the Internet to publish and push reports that Obama worked closely with Chicago political radicals prior to his election to the Senate. The McCain campaign had initially kept its distance from such claims, but in early October, and behind in the polls, McCain used TV ads and speeches to highlight Obama's links to former Weather Underground leader William Ayers.

Supporters of both candidates argue that such smears are aided, directly or indirectly, by the rival campaign. Michael Goldfarb, a blogger working for the McCain campaign, alleges that Democratic-leaning blogs such as the Huffington Post, DailyKos, and Talking Points Memo often publish reports that they originally got from opposition researchers working for the Democratic National Committee. In turn, those online reports are picked up by major media outlets, he said. On Sept. 1, just after Palin was picked as McCain's running mate, DailyKos showed video of a senior member of the Alaska Independence Party saying that the Alaska governor was a member of the party before she won her first mayoral election in 1996. For a couple of days, many major media outlets reported Palin's membership until the head of the AKIP apologized and said she had been incorrect, that only Palin's husband, Todd, had been a member. Most major media outlets did follow-up stories saying that Gov. Palin had not been a member of the party.

Charges of orchestrated smears are difficult to prove because Internet users can so easily hide their identity from rival campaign or independent investigators, said Lehane. For example, Tapperjapper's identity is kept secret by YouTube, and other Web site operators can hide their control of a Web site by hosting their sites at an Internet firm that offers anonymity to its customers.

To get the most from the Internet, campaign managers "have to cede some control" to their online allies, said Lehane. Such allies can provide an alternative "communications delivery system," which can offset the failure of the established media outlets to rapidly counter criticisms and smears, he said. "You can no longer to rely on the mainstream media to call foul... you have to defend yourself."

But top campaign managers also need to rise above the daily push-and-pull, said Dezenhall. Online criticisms or smears usually won't hurt a campaign unless they match a prevailing narrative about the party or candidate, he said. For example, the Republican Party has been tainted as the party of dirty tricks since Watergate, so the public is ready to believe that Republicans smear their rivals, he said. Similarly, the Democratic Party has been tainted as the culturally out-of-touch party of Barbra Streisand, making it easier to paint Obama as an elite outsider, he said. "At some level, some people will want to believe he's a Muslim, and you can't do anything about it," Dezenhall said. "The best thing that Obama can do is to... hammer the 'dirty tricks' narrative over and over again" in the hope that voters will dismiss Republican criticisms as smears, he said. "Whoever is on offensive wins, whoever is on defense loses."