Democratic presidential nominee Hillary Clinton on Monday made a final pitch to tens of thousands of voters at a massive rally in Philadelphia, urging them to reject her "loose cannon" opponent, Republican Donald Trump.

"There is a clear choice in this election, a choice between division or unity," Clinton said at the rally, a show of political force with her husband Bill, President Barack Obama and First Lady Michelle at her side.

"Between an economy that works for everyone or only those at the top, between strong, steady leadership or a loose cannon who could put everything at risk."