Bernie Sanders has officially confirmed his decision to run again for the US presidency in 2020.

He made the announcement in an email to his supporters this morning, saying that it was time to complete the "political revolution" that began with his previous campaign in 2016.

Despite losing the Democratic nomination to Hillary Clinton last time around, Sanders is hoping to repeat the energy of his first campaign and ultimately beat Donald Trump, whom he has called "the most dangerous president in modern American history".

Sanders is now 77 years old, but will his age be an issue?

Cal Thomas and Marion McKeone discussed this and more from the United States, including Trump's attack on former FBI director Andrew McCabe, who made explosive claims about the President in a CBS interview promoting his new book.