Former Vice President Joe Biden in a Wednesday speech slammed President Trump as a charlatan, arguing he takes advantage of frustrated middle class voters who have become his "targets.""These people aren't prejudice.

They're realistic. They're realistic. And they become targets to charlatans," Biden said, referring to middle class voters who supported Trump.

"And look what happens - like most charlatans throughout time, who seek to aggrandize themselves and consolidate their power, by always blaming the other."

Speaking at the Chicago Council on Global Affairs, Biden criticized the Trump administration's foreign policy, including the president's recent decision to de-certify the Iran nuclear agreement reached under former President Barack Obama.

"President Trump's America first slogan isolates us in the world at a moment when few if any of the threats - of today's threats - can be met without broad international effort and consensus, grounded in mutual interests and mutual respect, shared values," Biden said.

The former vice president, who is widely viewed as a possible contender for the 2020 Democratic presidential nomination, also critiqued the Trump administration's America first approach.

"This administration costs - well let me say it another way - it casts...global affairs to dog-eat-dog competition, a Hobbesian world in which for Americans to success others must lose, or fail," he said.

Biden also hit Trump as "childish" for using Twitter to communicate parts of his foreign policy and said the administration's red lines on North Korea send "signals that are dangerous."

"You know, big nations can't bluff and what the president doesn't realize, drawing all of these red lines with regard to North Korea and then not following up diminishes our power around the world, sends out signals that are dangerous," he said of Trump.

"And so we've got to stop this tweeting. We've got to stop this sort of-it is so - I've tried to stay out of the mosh pit, the president and I, Obama and I have, but it's childish. It's time to grow up. It's time to grow up and act like a real leader," Biden added, receiving a round of applause from the crowd.

Source: AFP