After a Super Tuesday that Bernie Sanders had hoped would showcase his dominance but instead established Joe Biden's dramatic comeback, the Vermont senator said, "Of course I'm disappointed," but also noted he had won the primaries in his home state of Vermont, Utah, Colorado and likely California.

"Now, I haven't seen the latest delegate count, but my guess is that after California is thrown into the hopper, it's gonna be pretty close. We may be up by a few. Biden may be up by a few. But I think we go forward, basically neck and neck," said Sanders, voicing confidence in his standing.

By 4 p.m. Wednesday, Biden had 494 delegates to Sanders' 425 and had won 10 out of the 14 states that voted Tuesday, according to CBS News' calculations. Sanders sought to remind reporters at his field office in Burlington that he was exceeding expectations.

Get updates from the campaign trail delivered to your inbox

"If everybody here thought that a year would come and go, and we would be either tied for first — a few votes up, a few votes down, delegates up or down — that is a pretty amazing achievement," he added.

Sanders admitted some pitfalls, including the fact that young voters, essential to his political revolution, have yet to show up in the numbers he was hoping to see.

"This is a campaign which is trying to bring, and it is not easy," he said. People who have not been involved in the political process so if you might want to ask me, maybe as a follow-up question, 'have we been as successful as I would hope in bringing young people in?' And the answer is no. We're making some progress, but historically, everybody knows that young people do not vote in the kind of numbers that older people vote in."

He expressed hope that this would not be the case after the primary process was settled, but his disappointment in the turnout of young voters was palpable.

"I think that will change in the general election, but I am honest — be honest with you," he said. "We have not done as well in bringing young people into the political process. It is not easy."

Sanders also talked about the ideological divide between him and Biden, who has in 48 hours become Sanders' biggest obstacle to the Democratic nomination.

"What this campaign, I think, is increasingly about is: Which side are you on?" he said. Sanders listed his familiar criticism of Biden on health care, trade, entitlements, the bankruptcy bill, and the Iraq War, using the refrain, "Joe is going to have to explain to the American people …"American people want. They want a serious debate on serious issues."

Sanders brought up his most consistent and oldest critique of Biden, the funding of his campaign and slammed him over the super PAC supporting his candidacy.

"Does anyone seriously believe that a president, backed by the corporate world is going to bring about the changes in this country that working families and the middle class and low-income people desperately need?" Sanders asked. He often reminds crowds that he does not have, want, or need a Super PAC.

He also contrasted their records on health care, trade, entitlements, the bankruptcy bill, and the Iraq War. Sanders used the refrain, "Joe is going to have to explain to the American people …" to highlight the contrasts.

Throughout his critique of Biden, Sanders said he did not want his campaign to "degenerate into a Trump type effort where we're attacking each other." He said that he looks forward to a serious debate on the issues.

He also told reporters that he had spoken on the phone a few hours earler with Elizabeth Warren, who failed to win any states on Tuesday, including her home state of Massachusetts, where she placed third.

"What Senator Warren told me is that she is assessing her campaign," he said. "She has not made any decisions as of this point. And it is important, I think for all of us, certainly me, who known Elizabeth Warren for many, many years, to respect the time and the space that she needs to make her decision."

Warren's departure from the race would likely help Sanders' standing in the races ahead. He's hoping to do well in Michigan, where he beat Hillary Clinton in 2016. Should he win, it would solidify his argument that he can build a coalition of urban and working-class voters. A loss would imply he is losing support, especially after failing to win Minnesota and Massachusetts.

"We are going in there with a full expectation and the hope that we will win," he said, calling it an "enormously important state" and one "I feel very comfortable in." Trade is one issue he expects to bring up in Michigan.

Although he is trying to emphasize his distance from the former vice president, Sanders is trying to highlight his own relationship with the president he served, Barack Obama. Sanders released an ad Wednesday morning featuring President Obama's praise of Sanders on some issues. Asked by CBS News what he hoped to achieve with that message, Sanders responded that though the two are not "best friends," he and Mr. Obama talk every so often. Sanders said that he wanted to combat "dishonest statements about my relationship with Obama, to say that I worked with him and respect him and look forward to working with him."

Though he welcomed the news Mike Bloomberg had dropped out of the presidential race, he predicted Bloomberg's financial support would buttress Biden's campaign and be used in negative ads targeting him.

"It's what the media has been talking about for months," Sanders said. "How do we stop Bernie Sanders? How do we stop a movement of working people and low income people? How do we stop a multi-generational, multi-racial movement, which is standing up for justice? And what you do is you get candidates out of the race to rally around Joe Biden and now, Joe will have behind him […] Obviously, as the ninth wealthiest person in this country who's worth some $60 billion dollars, I suspect we will see, you know, a lot of money coming into Biden's campaign, probably a lot of negative ads attacking me."