Two months before Election Day, questions of trust and honesty are weighing heavy in the race between Clinton and Donald Trump. Biden said the criticism of Clinton has been "veiled and unspecific," but she needs to show voters that she understands their challenges and pain.
"The truth is Hillary knows it's a problem. And she's trying to figure out how to remedy it," Biden told CNN about perceptions of Clinton's trustworthiness. "My advice to her the best way to remedy it is to talk about what you care about. Talk about it with some passion and people will see through it."
Democrats are sending their full bench to the campaign trail, with Biden and President Barack Obama working aggressively to keep the White House in their party's hands. They are set to campaign more than any sitting president and vice president have in a generation for their successors.
At a Labor Day rally here in Pittsburgh, Biden and vice presidential hopeful Tim Kaine appeared together Monday for the first time in this election cycle. Both men are trying to improve the Democratic ticket's standing with white working-class voters.
"People are looking for a ladder," Kaine told CNN. "They want to see there is a ladder that they can climb and that's what Hilary and I are talking about. At the end of the day, that will pose a comparison that is very, very stark."
A year after Biden decided against running for president himself, he said he is "100 percent" invested in helping Clinton. He said Trump was not qualified to be president, but acknowledged it was "an incredibly confusing year," and Democrats should not grow complacent.
"I just can't fathom what he'd do," Biden said of a Trump presidency. "The idea that he cares about the plight of middle-class people is just inconsistent with what he's done."
With both candidates facing record-high disapproval ratings, Biden said he worried Clinton could struggle to reach voters.
"This could be the most negative campaign in the history of modern politics," Biden said. "My question is, is anybody going to be able to break through what is just sort of a notion of a pox on both your houses?"
For Clinton, under constant siege over her use of a private email server as secretary of state
and facing questions over whether Clinton Foundation donors had improper access to her State Department
, polls have shown trustworthiness is her most significant weakness.
Asked whether Clinton had been successful trying to explain the controversies, Biden said, "It's been a moving target." But he added that he was "absolutely confident she is doing it by the book."
"She is going to figure out what she is going to say," Biden said, "to be crystal clear to the American people about what the relationship will be between the family and the foundation going forward."
One issue dividing the Democratic Party is trade, particularly the Trans-Pacific Partnership, a 12-nation accord that Obama is trying to win Congressional approval before his term ends. Kaine and Clinton oppose the agreement
, which Obama and Biden support.
Asked how he and the President could win over Kaine and Clinton, Biden declared: "We're not."
"They don't think it's a good enough deal to support. The President and I think it is," Biden said. "But the bottom line is we're going to attempt in a lame duck (session of Congress) to actually have a vote."
Eight years after Biden was tapped to be Obama's vice president, he offered one piece of advice for Kaine.
"Understand that the bureaucracy is gigantic," Biden said. "As well as you think you know it, take control of it, grab it by the throat. And make sure you follow up in detail on whatever initiative the president gives you."