Democratic debate: Senator Bernie Sanders attacked by opponents

US Senator Bernie Sanders has been attacked from all sides in the latest Democratic debate.

At times it dissolved into chaos, which is exactly what the critics of the self-described democratic socialist say will happen if he becomes the nominee.

One by one, the seven candidates walked onto the stage in Charleston, South Carolina, and they took aim at the man most likely to take on President Donald Trump.

"Bernie hasn't passed much of anything," former Vice President Joe Biden said.

"I think I'd make a much better president than Bernie," Senator Elizabeth Warren said.

"Do something for the people of America instead of a bunch of broken promises that sound good on bumper stickers," Senator Amy Klobuchar said.

"If you think the last four years has been chaotic, divisive, toxic, exhausting - imagine spending the majority of 2020 with Bernie Sanders against Donald Trump. Think about what that will be like for this country," former Mayor Pete Buttigieg said.

And that was the point they continually hit Sanders with - he is too left-wing to beat Trump.

With seven candidates, the moderators at times lost control and they all shouted over each other.

But that's what happens a week before the all-important Super Tuesday where 14 states vote for their Democrat of choice.

Sanders, who is leading Democratic polls, made the most of his time centre-stage.

"[There's a] misconception - and you're hearing it here tonight - that the ideas I'm talking about are radical. They're not," he said.

"In one form or another they exist in countries all over the world. Healthcare is a human right… everything is impossible until it happens."

In quoting Nelson Mandela, Sanders claims his fight to become president is not as far-fetched as his rivals make out.