Hillary Clinton lost the presidential election because she never figured out why she was running, according to Vice-President Joe Biden.

Biden, who campaigned for Clinton during the election campaign, said in an interview with the LA Times he thought there was pressure on Clinton to become the first female president.

"She thought she had no choice but to run," he told the newspaper. "That, as the first woman who had an opportunity to win the presidency, I think it was a real burden on her."

And although the polls seemed to suggest Clinton was likely to win the presidential election, Biden said there were indications Trump would be victorious when he watched footage of the now president-elect in Pennsylvania.

"Son of a gun. We may lose this election," Biden said he thought while watching the crowds. "They're all the people I grew up with. They're their kids. And they're not racist. They're not sexist. But we didn't talk to them.

"I don't think he understands working-class or middle-class people," Biden added.

Hillary Clinton
Vice President Joe Biden and Hillary Clinton at a ceremony on Capitol Hill in Washington, DC. Jonathan Ernst/ Reuters

"He at least acknowledged the pain. But he played to the prejudice. He played to the fear. He played to the desperation. There was nothing positive that I ascertained when he spoke to these folks that was uplifting."

Biden explained he did not believe the Democratic Party had addressed the fears of those people who had suffered economically, and said the election loss was not simply down to Clinton but to a number of factors the party must now address.