Harris, 54, who claimed to have had raised more than $1.5 million within 24 hours of announcing her campaign, will be the first Indian-American woman and only the second African-American woman to run for president.

Reports said CNN got an average of 1.957 millions viewers for the programme. The previous average of similar programmes was 1.119 million each.

Among other things, Harris spoke on gun violence at the programme.

"There is no reason why we cannot have reasonable gun safety laws in this country," she said.

"What's missing is the people in the United States Congress to have to courage to act the right way," she said amid applause.

"We can be the generation that ends gun violence. Every parent deserves to be able to send their children to school without being haunted by the potential horror of another killing spree," she tweeted.