The first US presidential candidates' debate using only questions submitted online by the public has been held.
The eight Democratic Party hopefuls were asked questions on issues ranging from the war in Iraq to health care, taxes and same-sex marriage.
The link-up by broadcaster CNN and the video-sharing website YouTube is being hailed as a political milestone.
Questions were chosen from nearly 3,000 submitted in the form of 30-second video clips posted on YouTube.
Analysts say online video could play a big role in the 2008 White House race.
Candidates from both parties have been trying to build up internet support using social networking and video-sharing sites, with Democratic Senator Barack Obama proving particularly successful.
The Republicans will be asked questions submitted via YouTube on 17 September in Florida.
Some of the strongest exchanges between the candidates were over the war in Iraq.
Ohio Representative Dennis Kucinich said he had voted against the war and blamed political game-playing for continuing the conflict.
"The Democrats have failed the American people," he said.
Illinois Senator Barack Obama also criticised his rivals in Congress who voted to support the 2003 invasion of Iraq.
"The time to ask how we're going to get out of Iraq was before we got in," he said.
Foreign affairs also provoked a clash between Mr Obama and the front-runner in the opinion polls, Senator Hillary Clinton.
Asked whether he would meet the leaders of Iran, Syria, Venezuela, Cuba and North Korea in his first year as president, Mr Obama said he would.
"The reason is this: that the notion that somehow not talking to countries is punishment to them, which has been the guiding diplomatic principle of this administration, is ridiculous."
Mrs Clinton, in comments designed to underline her political experience, disagreed.
"I don't want to be used for propaganda purposes. I don't want to make a situation even worse," she said.
Quirky and personal
Raising another contentious issue for Americans, a lesbian couple asked if the candidates would allow them to be married.
Mr Kucinich said he would. Senator Chris Dodd of Connecticut said he would not.
Candidates disagreed about marriage rights for gay couples
After being pressed on the issue, North Carolina Senator John Edwards said he did not support gay marriage.
"But I think it's wrong for me as the President of the United States... to use my faith to deny anyone their rights," he added.
CNN's politics team selected the questions to be asked. The videos, which ranged from high-production numbers to grainy webcam shoots, were often quirky and very personal.
In one, a 36-year-old cancer patient called Kim pulled off a wig to reveal hair loss from chemotherapy as she asked about health care for those without health insurance.
About 10 members of the public who submitted questions were invited to South Carolina to watch the debate and were given access to the candidates afterwards in the "spin room", where they usually talk to journalists.
The candidates have already tried to engage with the YouTube audience, with Senator Joseph Biden, for example, uploading a guide telling supporters how to submit a question on Iraq.
Some commentators, however, have suggested the excitement over the debate may turn out to be more hype than a real turning point in US politics.