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Optimistic as ever, Vice President Joe Biden portrayed the United States as a nation of hope, goodwill and strength in a speech to the Democratic National Convention while offering a dire warning of the risk of electing Republican presidential nominee Donald Trump.

As polls show Trump resonating among white, working-class voters, especially those without college degrees, Biden used his blue-collar bona fides to paint Trump as a fraud who has “no clue” about the needs and struggles of the middle class.

“This guy does not have a clue about the middle class. Not a clue,” Biden said.

“His cynicism is unbounded, his lack of empathy and compassion can be summed up in a phrase I suspect he's most proud of having made famous, ‘You're fired!’ Think about that,” Biden said.

“He's trying to tell us he cares about the middle class, give me a break. That's a bunch of malarkey,” he added.

In contrast, Biden said, “Hillary understands” the plight of parents who can’t afford to send their child to college or the wife fearful that a medical emergency will cause economic catastrophe.

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“Hillary gets it,” he said.

Biden then broadened the things he thinks Trump is clueless about to everything: “Actually, he has no clue, period.”

The crowd erupted in sustained chants of, “Not a clue.”

Biden, who has experienced a long career mostly full of political success, has also lived through personal trauma. Shortly after his election to the Senate at the young age of 29, his wife and infant daughter were killed in a car crash. And just last year his son Beau died of brain cancer. He contemplated a presidential run this year but was not ready after the death of his son.

Biden mentioned his son Beau, calling him “an incredibly fine young man.” He also called President Barack Obama “one of the finest presidents we’ve ever had.” But he spent most of his time on stage insisting that Trump is ill-prepared and too irrational to be president.

Biden said Trump’s shortcomings extend beyond U.S. borders.

“The threats are too great, the times are too uncertain to elect Donald Trump as President of the United States,” Biden said.

We cannot elect a man who exploits our fears of ISIS and other terrorists, who has no plan whatsoever to make us safer; a man who embraces the tactics of our enemies: torture, religious intolerance, you all know.

“We cannot elect a man who belittles our closest allies while embracing dictators like Vladimir Putin,” Biden said. Adding the U.S. cannot elect “a man who seeks to sow division in America for his own gain and disorder around the world; a man who confuses bluster with strength.”

Just hours earlier on Wednesday, Trump encouraged the Russians to obtain Democratic nominee Hillary Clinton’s emails from her private server, a statement that shocked and worried national security observers.

“We simply cannot let that happen as Americans,” he said.

Biden said Americans are strong and push through difficult times.

“We endure. We overcome and we always, always, always move forward,” he said. “We lead not by the example of our power but by the power of our example.”

And, he concluded, “Hillary Clinton will lead the next chapter.”