'You have no idea': Hillary Clinton's biting debate response

The moment presidential candidate Joe Biden told Donald Trump to "shut up" in a fiery exchange during the US election debate has everyone talking.

Even former presidential candidate Hillary Clinton has weighed in with a cheeky response.

Writer Jill Filipovic took to Twitter to say Mr Biden delivered the "line of the night".

"I so feel for Hillary right now because I'm positive she wanted to say (shut up) and couldn't," she said.

"You have no idea," Ms Clinton responded.

Mr Biden was asked about Supreme Court packing and if he would support it.

President Donald Trump and Democratic presidential candidate former Vice President Joe Biden participate in the first presidential debate. Photo / AP

That relates to the idea among some Democrats that if Mr Trump gets his nominee for the Supreme Court confirmed, Mr Biden should then expand the court to add two more justices if he's elected.

Mr Trump on Saturday nominated Amy Coney Barrett to the Supreme Court, picking a strong conservative to replace the late liberal justice Ruth Bader Ginsburg.

With Republicans almost certain to confirm Judge Barrett, Mr Trump will have been able to tilt the High Court to the right on the eve of his difficult re-election attempt.

Democrats have complained that Mr Trump should not be able to name a new justice so close to the presidential election.

You have no idea.

— Hillary Clinton (@HillaryClinton) September 30, 2020

During the debate Mr Biden didn't answer the Supreme Court question directly and instead said Americans should speak with their votes.

But the President wasn't letting him off the hook.

"Are you going to pack the court?," Mr Trump asked.

Mr Biden said he wasn't going to answer the question.

"Why wouldn't you answer the question? Radical left," Mr Trump shot back.

"Will you shut up, man?," Mr Biden responded, as the exchange continued.

"Who is on your list, Joe? Who is on your list?"

Donald Trump and Hillary Clinton during presidential debate in 2016. Photo / AP

"This is so unpresidential. I'm not going to give a list."

Moderator Chris Wallace, a veteran political journalist from Fox News with a reputation for asking tough questions of both sides, interjected that the segment had ended.

"We've ended this segment," he said.

"That was a productive segment, wasn't it? Keep yapping man," Mr Biden said.

Earlier in the exchange Wallace kept asking Mr Trump to let Mr Biden finish what he was saying, with the President constantly cutting him off.

"He doesn't know how to do that," Mr Biden said.

"Please let him speak, Mr President," Wallace kept saying.

Mr Biden then called Mr Trump a clown.