"He's not a bad man," Biden told CNN's Chris Cuomo on "New Day." "But his ignorance is so profound, so profound."
"I bet he couldn't carry his bag 18 holes in one of his own golf courses, speaking of energy," Biden said. "Can you imagine the President getting up at 3:30 in the morning and tweeting vitriol?"
Biden was referencing Trump's late night Twitter rant on Friday, when he took to the social media at 3 a.m. ET to slam the media and then two hours later, opened up Twitter again and quickly went from venting to slandering former Miss Universe Alicia Machado for an alleged sex tape that the campaign has yet to provide evidence for.
In the wide-ranging interview with CNN, Biden praised Clinton and said he's working hard to get her to the White House and slammed Trump for his comments on the military, praise for Russian President Vladimir Putin and the possibility that he might not be paying taxes.
Biden on Trump's taxes
When asked about The New York Times report
about Trump's leaked income tax returns published Saturday night revealed that Trump might have avoided income taxes for 18 years after declaring a $916 million loss in 1995, Biden said paying taxes is "about making sure you did your part for the country."
The Times obtained one page of his New York State resident income tax returns as well as the first page of New Jersey and Connecticut nonresident returns -- it did not look at his federal return. CNN has not independently verified the documents' authenticity, but Trump's campaign has not denied any facts reported by The Times.
"Since when does somebody who lives at the top in the world, in a penthouse overlooking the world, be in a position that he doesn't feel any obligation at all to pay any federal income tax to support the military, to support education, to support our foreign policy?" Biden said about Trump. "Since when is that a patriotic thing to do? Can you imagine any other president, any other president, just ever say that and be proud of that? I can't fathom it."
And Biden added that despite Trump's promises to challenge the status quo, his proposed tax plan will preserve the tax breaks he took advantage of.
"What he's proposing in the tax cut would lock in all of those special interests from real estate folks and cut their taxes even more," Biden said. "This is all about Trump. This is all about Trump."
Biden continued: "What's that say about all the people here? Are they all suckers for paying their taxes, because they can't hire a tax lawyer, because they couldn't make significant contributions to try to change the law to benefit themselves? Come on, man. That's just not right."
'How can (Trump) be so out of touch?'
Biden also responded to Trump's comments Monday about veterans suffering from PTSD, calling him "ignorant" of the sacrifice of service men and women. Trump said of veterans suffering that if "you're strong and you can handle it but a lot of people can't handle it."
The vice president invited Trump to the "battlefield" with him in Afghanistan and Iraq so that Trump could experience what the "these kids are going through" and the "sacrifices they're making."
"I was asked to present a Silver Star to a young man who had jumped into a burning Humvee to pull out his buddy after an IED exploded," Biden said. "And the kid died. The commanding general ... asked me to pin on a Silver Star, when I was there. You know what the kid said to me? 'I don't want it. I don't want it. He did not live, sir. He did not live, sir.' That kid probably goes to sleep every night with a nightmare."
"How can (Trump) be so out of touch and ask to lead this country?" Biden asked.
'I'm working like hell for Hillary'
Biden, who decided against running for the White House himself after his son, Beau, died from cancer, said Clinton would make a "first-rate president."
"I'm working like hell for Hillary," he said. "Every time she expresses emotion, she gets clobbered. She gets clobbered ... (But) I know her. I know she cares ... (Trump) doesn't deliver anything that's gonna change (people's) lives."