Philadelphia, Jul 28 (IANS): US Vice President Joe Biden in a speech at the ongoing Democratic National Convention (DNC) warned over electing Republican presidential nominee Donald Trump, saying the real estate mogul 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," NBC News quoted Biden as saying on Wednesday night on the second day of the DNC here.

"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," the Vice President said.

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

In contrast, Biden said about Democratic presumptive nominee Hillary Clinton that she "understands" the plight of parents who cannot afford to send their child to college or the wife fearful that a medical emergency will cause economic catastrophe, NBC News noted.

"Hillary gets it", he said.

Biden then went to emphasise things that Trump was clueless about, saying "Actually, he has no clue, period."

The crowd erupted in chants of, "Not a clue".

Biden said Trump's shortcomings extend beyond US borders.

"The threats are too great, the times are too uncertain to elect Donald Trump as President of the US," NBC News reported citing the Vice President as saying.

Earlier on Wednesday, Trump encouraged the Russians to obtain 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.

However, he concluded the speech by saying, "Hillary Clinton will lead the next chapter", NBC added.

The DNC started on Tuesday night. First Lady Michelle, former President Bill Clinton addressed the convention which will run until Thursday night when the former Secretary of State will formally accept her party nomination for the presidential elections.