Former Vice President Joe Biden arrives at the Wilmington, Del., train station on Thursday after announcing his candidacy for the Democratic nomination for president. (Matt Slocum/AP)
Steven Levingston is the nonfiction editor of The Washington Post. He is author of "Barack and Joe: The Making of an Extraordinary Partnership", "Kennedy and King: The President, the Pastor, and the Battle over Civil Rights", “Little Demon in the City of Light: A True Story of Murder and Mesmerism in Belle Époque Paris.

When Joe Biden finally announced his presidential candidacy on Thursday, he seemed almost unrecognizable — no longer the avuncular sidekick Americans came to know during the Obama administration. In a sober three-minute video, he frowned and fretted as frightening clips of neo-Nazi marchers rolled. “We are,” he declared, “in the battle for the soul of this nation.” His voice was firm, his gaze sharp, his lips tight.

The campaign video begins Biden’s almost impossible journey of reinvention. For eight years, his personality and his success as a political leader were yoked to President Barack Obama. Obama’s glory was Biden’s glory: The vice president shone in the reflected light of a historic president. This link makes Biden an immediate leader in the Democratic presidential race, but it also traps him: He is identified perhaps inescapably as Obama’s wingman. Now, Biden needs to separate himself from the source of his popularity — the former president — and define himself in his own right without sacrificing the benefits of his association with Obama.

In politics, and even a little bit in his personal life, Biden was married to Obama. They shared high-profile man-hugs on stage at rallies, walked arm-in-arm through the White House, and shed tears at funerals and other moving events such as Biden’s Medal of Freedom ceremony. Photos showed the duo on their presidential adventures — in the Situation Room, at Ray’s Hell Burger in Arlington, Va., at a memorial for shooting victims in Orlando, on the White House putting green, in St. Anthony of Padua Church in Wilmington, Del. Toward the end of their partnership, memes commemorating it proliferated online. But Obama was the centerpiece: It was the intense interest in him that fired the spotlight onto their camaraderie.

Biden seems to grasp that Obama won’t be a springboard for the next phase of his political career — a role that the former president had already declined to play during his possible presidential bid in 2016, when Obama supported Hillary Clinton. “I asked President Obama not to endorse and he doesn’t want to,” Biden claimed on Thursday, soon after releasing his video. “Whoever wins this nomination should win this on their own merits.”

Success on his own has proved elusive for Biden. His two previous White House bids did not go well. He dropped out of the 1988 race under a cloud of plagiarism accusations, and he ended his 2008 campaign after ranking fifth place in the Iowa caucuses. President Trump was cruel, but not entirely wrong, when he tweeted recently that Biden “never got above 1 percent. And then, Obama came along and took him off the trash heap, and he became the vice president.” Biden seems eager to prove himself now. “I’m gonna do this based on who I am, not by the president going out and trying to say, ‘This is the guy you should be with,’ ” he said Friday on ABC’s “The View.”

Emerging from Obama’s shadow is fraught with risks. Detached, Biden may be less attractive and therefore less popular with voters. This explains why, even as he steps out on his own, he espouses a campaign refrain of running as “an Obama-Biden Democrat.” The coming primaries will test his solitary appeal; should he falter, it might be because of the dimming Obama glow.

Long before he linked up with Obama, Biden was already a jumble of good feelings and impetuousness. But his loose tongue littered the landscape with potentially damaging gaffes. Just weeks before the 2008 election, Biden warned voters that the inexperienced Obama was likely to be tested by a foreign power; and he famously came out in favor of same-sex marriage before the president was ready to do so. None of Biden’s slip-ups proved terribly detrimental, so he emerged as someone who was sometimes just too authentic or enthusiastic. The Obama shield saved him from the repercussions of his impulses.

But without Obama, Biden loses the easy popularity that shield provided, and his stumbles take on a graver significance. The stakes are higher now when he makes women uncomfortable by touching them, as several have said he did. Anita Hill said this past week that she wants “real accountability” for the dismissive way he treated her during Clarence Thomas’s Supreme Court confirmation hearings.

As a guy beloved by a huge swath of the nation for the way he played off a subdued straight man, Biden will be less free to try his wit than he was in the past. Soon after women complained about his unwanted affection, Biden joked that he had permission to hug a man who introduced him at a conference of the International Brotherhood of Electrical Workers, a quip that stirred further acrimony. Jovial Joe must now prove that he can be as sober and steady as his former boss.

Perhaps that explains the intensity of his announcement video and the absence of the Biden smile, charm and playfulness on screen. After months of researching my new book, “Barack and Joe: The Making of an Extraordinary Partnership,” I couldn’t help thinking that in the video, solitary Biden looked a little diminished, a little less than what he once was, even a little lonely.

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