All eyes will be on Kamala Harris and Donald Trump as they come face to face for the first time this afternoon.\xa0
The first \u2014and possibly only debate\u2014 will be broadcast out of Philadelphia, the biggest city in the battleground swing state of Pennsylvania.\xa0
US correspondent Richard Arnold told Mike Hosking the polls show there's only a few points either way in many states.\xa0
He says it will be a crucial debate, with no live audience, no notes, microphones will be muted when it's not a candidate's turn to speak, and only mediators will ask questions.\xa0
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