ST. PETERSBURG, Florida (CNN) -- It was one of the most talked about moments in last year's congressional campaign.
Democratic candidates view a YouTube question during their July debate.
"Let's give a welcome to Macaca, here. Welcome to America and the real world of Virginia."
That was Sen. George Allen's controversial remark to a young campaign aide working for his opponent, Jim Webb, who had shown up at an Allen rally.
The aide caught the comments on camera and the video became an instant hit on YouTube. It was arguably one of the reasons Allen lost a razor-thin election to Webb. The Democrats' victory in that pivotal Virginia race helped them win control of the Senate.
It also sank Allen's ambitions of running for the White House.
"If not for YouTube, Allen would most likely be one of the front-runners today for the GOP presidential nomination," CNN political editor Mark Preston said.
Those Republicans who are running for the presidency will square off Wednesday in St. Petersburg, Florida, in the second of two CNN/YouTube debates. Democratic candidates took questions from YouTube users in July. Watch some of the offbeat questions you're not likely to hear »
The race for the White House picked up where the battle for Congress left off, with the current presidential campaign having its own share of YouTube hits.
"You cannot go to a 7-Eleven or a Dunkin Donuts unless you have a slight Indian accent. I'm not joking," said Sen. Joe Biden of Delaware, in comments that were widely watched on YouTube after being caught on camera. The Democratic presidential candidate was joking, but his words came back to hurt him.
It was a similar situation for Sen. John McCain. The Arizona Republican and White House hopeful was joking with supporters at a campaign event in South Carolina earlier this year when he said "remember that old Beach Boys song, bomb Iran. Bomb, bomb, bomb." The event was captured on camera and instantly became a YouTube hit.
McCain was forced to deal with the political damage done by his words.
By giving old debate clips new life, YouTube is also forcing presidential candidates to explain past positions.
When asked during a 1994 Senate debate in Tennessee whether he supported laws that prohibit abortions for convenience, Republican Fred Thompson responded by saying, "I do not believe that the federal government should be involved with that process."
That old clip became a big hit on YouTube. While Thompson's record in the Senate was consistently anti-abortion rights, the former senator and GOP presidential candidate was forced to explain exactly where he stood on abortion.
Thompson's GOP rival Mitt Romney faced a similar situation.
"I believe that abortion should be safe and legal in this country," Romney said in a 1994 Senate debate against Massachusetts Democrat Ted Kennedy.
Romney has since changed his position on abortion, but his rivals accuse him of flip-flopping on this issue, and the re-airing of this old debate clip on YouTube probably didn't help. But to the Romney campaign's credit, they fired back with their own video sent to YouTube in which Romney explained and defended his positions.
"While candidates can put their own message out online -- be it on an official Web site, through a Web video, on a Facebook page -- it can be the unflattering and unofficial YouTube video that really resonates," said CNN Internet reporter Abbi Tatton.
"Has it had an impact? Of course. But, I think to me what's more interesting is from the strategist point of view, which is when to react and when not to react to YouTube," added Amy Walter, editor-in-chief of National Journal's Hotline and a CNN political analyst.
The candidates also are learning how to harness the power of YouTube rather than just reacting to it.
"I promise you I won't sing," Sen. Hillary Clinton of New York said in a video her Democratic campaign for president submitted to the Web site.
YouTube this year has spotlighted one candidate each week, allowing the candidate to ask anything they want.
"What do you think our campaign song should be?" asked Clinton.
Users can talk back. Some even sung back in response to Clinton's question.
And then there was the [Barack] Obama Girl, who sang, "I gotta crush on Obama."
The Illinois Democrat's campaign wasn't behind the video that millions saw on YouTube, but the buzz probably didn't hurt his bid for the nomination.
YouTube is empowering average Americans to impact the political process like never before. Candidates don't have total control of their message, and that's forcing them to change the way they campaign.
"It's letting people get closer to the process," Tatton said. "Whether asking a question directly of a candidate on YouTube, organizing supporters on social networking sites, or raising record fundraising dollars through a candidate's Web site, voters can do it all right there online.
"The candidates have to recognize this is where people, especially young people, are participating."
In July, the Democratic White House hopefuls gathered in Charleston, South Carolina, for a CNN/YouTube debate. The questions to the candidates came from average Americans, via YouTube.
While the question posed by a talking snowman may be the most memorable from the debate, the question on whether the candidates would meet with unfriendly dictators during their first year in office as president made an impact.
Obama responded by saying that "the notion that somehow not talking to countries is punishment to them, which has been the guiding principle of this administration, is ridiculous."
Rival Clinton pounced on Obama's response, calling his answer naïve. The controversy grew and lasted for weeks. And the fireworks were sparked by a question from an average American. E-mail to a friend