In what is being described as a first for U.S. politics, Americans are being offered the chance to participate in a debate that will be driven by video questions uploaded to YouTube, the popular video-sharing website.

So far more than 1,500 questions have been posted to the site. Of those, debate organizer CNN will select about two dozen questions to put to Democrat presidential candidates in Charleston, North Carolina on July 23.

CNN's Anderson Cooper, who will be moderating the debate, said the response has been tremendous so far, and questions will be accepted right up until just before the debate begins.

He told Â鶹´«Ã½net that CNN is receiving a wide variety of questions, asked in a wide variety of ways, which promise to give the debate a unique flavour.

"We're used to moderators asking questions or a panel of moderators or a town hall format," Cooper said.

"This is really anybody -- people in hospitals, in their living rooms, in their beds, on the street -- there is another dimension to these questions because we're seeing the people, we are sort of entering their lives for some 30 seconds and that really is something that we have not seen before."

One of those video questions is from Kim, a 36-year-old mother of two who appears to be sitting in her bedroom, speaking into a webcam, explaining that she hopes to one day be a "future breast cancer survivor." Kim says she has gone for years without health insurance and asks the candidates what they would do, as president, to ensure that low-cost or free preventative medicine is provided to all Americans.

The questions that will eventually be shown to candidates are being chosen by a panel that includes Cooper and a number of producers from CNN. He said the group has been sitting in a room and poring through the hundreds of submissions, trying to whittle down the list to a manageable number.

CNN looked at the possibility of allowing viewers to go online to select the questions that would be put to the candidates, but eventually decided there was no way to ensure supporters of specific candidates didn't try to manipulate the debate.

He also said that the most viewed question currently posted on YouTube is about whether the candidates believe California Governor Arnold Schwarzenegger is a cyborg.

"It's not necessarily a question that you want all of the candidates to have to weigh-in on," Cooper said.

"There are obviously very important issues out there. The questions, we want them to be responsible, but at the same time representative of all of the questions that we have been receiving."

Cooper said the organizers are trying to ensure the debate is one of the most democratic ever held.

"The fact is all of these questions come from viewers and from people who want to submit them and so really there are no ground rules, no limitations other than the 30-second time limitation," Cooper said.

Cooper said the submissions cover a broad range of issues and topics, with a number of questions emerging on education, healthcare, the war in Iraq, gay rights and ongoing violence in Darfur.

During the debate, some of the questions will be directed at specific candidates while others will be asked of all the candidates.

User-generated online videos have played a large role in this campaign so far. Popular videos that have made their way onto YouTube include Bill and Hillary Clinton's "The Sopranos" parody, a music video dubbed "I got a Crush on Obama," and John Edwards combing his hair to the strains of "I Feel Pretty."