Joe Biden confuses granddaughter for dead son Beau

Joe Biden has been caught in an awkward gaffe after mixing up his family members at a campaign rally.

Appearing in Philadelphia just hours before polls close, the Democrat contender took to the stage with his granddaughter Finnegan.

"This is my son, Beau Biden who a lot of you helped elect to the Senate in Delaware," he said, putting his arm around her shoulder.

Beau was the attorney-general of Delaware and wasn't elected to its senate.

He then compounded the slip-up by calling Finnegan by her cousin's name.

"This is my granddaughter, Natalie. Oh no wait, I got the wrong one," Biden said.

Biden, who has a speech impediment, is known to be gaffe-prone and has made multiple family blunders in the past. Earlier in the year he confused his wife, Jill Biden, for his sister Valerie during a speech.

"By the way, that's my little sister Valerie, and I'm Jill's husband... oh no, you switched on me! This is my wife, this is my sister!" he said.

Later in the campaign he apologised for telling a black radio host that he "ain't black" if he was thinking about voting for Trump.

In 2017, Biden was blasted for making comments about children "jumping on his lap" when he worked as a lifeguard.

"I sit on the stand and it'd get hot... I got hairy legs... and the kids used to come up and reach in the pool and rub my leg down so it was straight and then watch the hair come back up again," Biden said during a speech.

"So I learned about roaches and I learned about kids jumping on my lap... I love kids jumping on my lap."