Claims of voter fraud are already hanging over the US election as millions of Americans head to the polls. 

Almost a third of eligible voters have cast an early ballot. 

Experts say the result could go either way, with Donald Trump and Kamala Harris still neck-and-neck in the key battleground states.  

FSN Correspondent Nick Harper told Ryan Bridge there are fears Trump will sow confusion and misinformation by calling his win prematurely. 

He says if Trump were to lose, it's likely he will claim the vote was rigged against him. 

Harper says it may be days until the final results are clear. 

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