“Short of Joe Biden entering the race, Sanders on paper starts off with more advantages than anybody else. He’s got the largest list; he’s got the most intense following that has stayed with him since 2016; he has a proven ability to fundraise from his small-dollar base,” said Brian Fallon, a Democratic strategist who was the spokesman for Clinton, leading the public charge against Sanders last time around. “He’s in the exact opposite position that he started off the 2016 campaign in.”

The Democrats running against him assume that this won’t last. But he’ll raise millions, get 20,000 people at his rallies, and make them all look junior varsity in comparison. Still, they’re confident that he won’t be able to maintain that over the next year.

Peter Beinart: Bernie Sanders offers a foreign policy for the common man

Sanders running when he’s part of a big field of enticing candidates is a whole lot different from Sanders running as the single fresh alternative to a candidate who never inspired much passion throughout her entire career. He could burn out, get eclipsed by some of the newer forces in the party, and have to answer for all the parts of his record and background that didn’t get full scrutiny when he was a novelty nowhere near winning in 2016.

If nothing else, there could certainly come a point late in the game, much like what happened with Howard Dean in 2004, when Democratic voters look at him and say they just can’t take seriously the idea of Sanders actually beating Trump, or actually being the commander in chief and sitting behind the Resolute Desk in the Oval Office as the 46th president of the United States.

At least that’s what his rivals are telling themselves. Because that’s how races have always gone up to this point. Except, that is, for 2016, when Sanders became a bizarre breakout sensation and the country put Trump behind that desk as the 45th president.

No matter what, his candidacy seems set to reshape the dynamics of the race.

Sanders has moved quickly in an attempt to show that he’s a more serious candidate than four years ago, when he announced his campaign during a break from the Senate floor, gave a few harried answers to the questions from the few reporters who had showed up, and then said he had to get back to vote.

This time, he started with a carefully constructed rollout, with a slick announcement video, a sit-down interview on CBS This Morning, and a media tour. “Sisters and brothers,” he wrote to his huge email list Tuesday morning, “together, you and I and our 2016 campaign began the political revolution. Now, it is time to complete that revolution and implement the vision that we fought for.”

A full operation is being put together, with the assumption that he will have well over $200 million in online fundraising to draw from. That includes top leadership of the campaign meant to illustrate the diversity of his support, demographically and geographically. Faiz Shakir, a former aide to Harry Reid, is leaving his job as the political director of the American Civil Liberties Union to be the campaign manager. In addition to his deep political experience, he will be the first Muslim presidential-campaign manager in history. Analilia Mejia, an organizer of Colombian and Dominican descent who most recently directed the Fight for $15 and Earned Sick Days campaigns in New Jersey and previously worked for the New Jersey Working Families Party, will be the political director. The deputy political director will be Sarah Badawi, who was most recently the government-affairs director for the Progressive Change Campaign Committee, a liberal group that led the effort to draft Elizabeth Warren into the 2012 Senate race, and later worked on her campaign.