The provocative comment was made by Mark Dolan during his talkRADIO show. The Duchess of Sussex is known to be estranged from a number of her own family members including father Thomas Markle, who previously discussed their strained relationship in his own Channel 5 documentary.
Mr Dolan added: “If America is the greatest nation on earth, we are all in trouble.”
During the debate in Cleveland Mr Trump and Mr Biden over coronavirus, the economy, racial justice and law and order.
Discussion turned acrimonious with Mr Biden calling the president racist and asking him to “shut up”, whilst Mr Trump launched personal attacks on Mr Biden’s son.
At times the moderator, Fox News’ Chris Wallace, seemed to lose control as the two men talked over each other.
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Some of the worst clashes came during a segment on the Supreme Court during which, addressing his rival, Mr Biden said: “Folks, do you have any idea what this clown is doing?”
Mr Trump is attempting to push through his Supreme Court nominee to replace Ruth Bader Ginsburg ahead of November’s election.
Controversially Mr Trump repeated his unverified claim the election is being rigged and indicated he may not respect the result.
Asked if he’d accept the outcome he said: “If it is fair election, I am 100 per cent on board, but if I see hundreds of thousands of ballots being manipulated, I can’t go along with that.
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“This is going to be fraud like you’ve never seen.
“We might not know for months because these ballots are going to be all over.”
The Duke and Duchess of Sussex announced they planned to step down as senior royals in January.
They have since left the UK and moved to Meghan’s home state of California.
According to a recently published book, ‘Finding Freedom’, a rift emerged between Prince William and Prince Harry during his relationship with Meghan.