Biden doubles down on warning of Sanders nomination, concedes New Hampshire an 'uphill battle' The former vice president sat down with George Stephanopoulos on Saturday.

Former Vice President Joe Biden intensified his warning to Democrats that nominating Sen. Bernie Sanders could lead to a stinging defeat in November, but he vowed to "work like hell" to help elect the Vermont senator if that's who wins the party's nomination.

Biden, facing the possibility of yet another disappointing finish in this week's New Hampshire primary, and coming off what he described as a "gut punch" by placing fourth in the Iowa caucuses, insisted that he is not "writing off the state," despite his overt attempt at Friday night's debate to downplay expectations for his performance.

"When you're running against two people who are neighboring senators, you know the deal," Biden told ABC News Chief Anchor George Stephanopoulos in an exclusive interview. "Bernie won here, the neighboring senator, by 20 points last time. So I, I think, it is an uphill fight. But I think it's a fight we'll do well in."

Since heading to the Granite State ahead of Tuesday's primary, Biden continued his pointed attacks on former South Bend, Indiana, Mayor Pete Buttigieg, noting his lack of experience and paltry support within the African American community, and on Sanders, for calling himself a "Democratic Socialist."

'It's gonna go all the way down the line': Biden on Sanders' down ballot effect

Following a debate that featured numerous confrontations between Biden and Sanders over health care, foreign policy and electability, Biden again warned that nominating the self-avowed socialist is too risky.

"I think it's gonna be incredibly more difficult. I'm not gonna say we -- look, if I don't get the nomination and Bernie gets it, I'm gonna work like hell for him. But I tell you what, it's a bigger uphill climb, running as a senator or a congressperson or as a governor on a ticket that calls itself a Democratic socialist ticket," Biden told Stephanopoulos.

Biden, as he has done during recent stump speeches, argued that nominating Sanders would force Democrats up and down the ballot to cope with the potential downside of being associated with "a socialist," a label President Donald Trump could attack and exploit.

"It's gonna go all the way down the line. That's what's gonna happen. You gonna win in North Carolina? You gonna win in Pennsylvania? You gonna win in those states? In the Midwest?" Biden continued. "I didn't put the label on Bernie. Bernie calls himself a Democratic socialist."

Biden on Buttigieg: 'Barack Obama was a different story'

Biden also continued to criticize Buttigieg, telling Stephanopoulos that although he liked the former mayor, he wasn't sure whether the 38-year-old had enough experience for the nation's top job.

"Pete Buttigieg has been nothing more -- he's a good guy, I like him and he's a smart guy -- but he's been the mayor of a city smaller than the city we're in now," Biden said. "And so what has he done? What has -- who has -- he pulled together? Does he know any of the foreign leaders?"

Biden stressed his criticism wasn't an offensive tactic, rather defensive, following Buttigieg's assertion that the former vice president is simply using the "same Washington playbook" against Trump leading up to the 2020 election.

"Let's get somethin' straight here," Biden continued. "I didn't attack Pete. Pete's been attacking me. He's been saying the reason we're in the problem we're in now is because of the recent past. That's eight years of Obama and me. I don't get that. I don't understand that. And I think he has completely misunderstood or misrepresented my record."

When pressed by Stephanopoulos about his previous assessment in 2007 that then-senator Barack Obama didn't have the experience needed to be president, Biden pushed back on any comparison of Obama to Buttigieg.

"I mean, Barack Obama was a different story. Barack Obama came from a large state, he was a United States senator and he had run before," Biden said. "He had a clear vision of what he thought the world should look like, and so on. ... It's a very different situation."

Trump's acquittal was 'the worst thing'

Biden, reacting to the Senate's decision earlier this week to acquit Trump on charges that he abused his power and obstructed Congress' investigation into whether or not he pressured Ukraine's president to open an investigation into Biden and the 2016 election, said he worried the verdict has only emboldened the president.

"The worst thing that happened was acquitting Trump, when they acknowledged that he interfered," Biden said. "... to try to get a foreign power to say something negative about me or my son. The foreign leader wouldn't do it. ... And so look what's happened. I'm worried this guy's got just a free pass now on anybody."

Despite his own personal frustration over Trump's attacks on his family, particularly his son, Hunter, Biden said he can't allow his "anger" to get in the way of his campaign message.

"I can't let my anger overcome the desire, the need to have to unite, heal this country," Biden said." I've gotta move beyond me, beyond my family, because this is about your families. It's about everybody else's family. Not mine."