Vice President Joe Biden believes Bernie Sanders will eventually back his Democratic primary rival Hillary Clinton, telling NPR in an interview that Sanders had confided in him about the decision.

"Oh, I've talked to Bernie," Biden said in an interview Thursday. "Bernie's going to endorse her. This is going to work out."

He added that "Democrats are coalescing even before this occurs."

But Sanders himself pushed back against the vice president's statements, telling MSNBC on Thursday that the two men had last chatted weeks ago.

"I talked to Joe, I think it was three weeks ago," Sanders said. "Look, on that issue we are trying to work with Secretary Clinton's campaign on areas that we can agree."

The Vermont senator, however, said of endorsing Clinton: "We're not quite there yet."

Last week, Sanders said he would like to see the former secretary of state embrace certain progressive ideas before giving his full-throated support.

"I want her to say among other things, we have a crisis in higher education -- public universities and colleges should be tuition free. Raise the minimum wage to $15 an hour," Sanders said in an interview with "CBS This Morning." "I believe that healthcare should be a right of all people. I would love her to say that and I would love her to move aggressively to make that happen."

Biden will be joining the party's presumptive nominee on the campaign trail for the first time next week, visiting his hometown of Scranton, Pennsylvania for a state Democratic party event.

"Those folks back home know me. And they know my shortcomings, and I have a lot of them, and they know my strengths," Biden told NPR.

Biden has greater appeal to the largely white working class population in places like Scranton -- more so than Clinton. YouGov data from May-June shows that among non-college-educated whites, Hillary Clinton net favorable rating of -40 percent, compared to a net favorable of only -10 percent for Biden. Among Democrats and those who lean Democratic, Biden has a 52 percent net favorable rating compared to 30 percent for Clinton.

Biden hopes to persuade some of those voters that Clinton deserves their votes.

"I understand the hardest thing to do is not writing the check. The hardest thing is vouching. When you vouch for them you say 'I'm putting my reputation on the line, I believe this person is a good person, has character," he said. "You're putting your rep on the line, you're saying, 'I think this person has character.' And that's what I'm prepared to do for Hillary."

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