Joe Biden is one of the few Democratic Party figures formidable enough to draw nuclear opposition before he even gets into the race. If the colonial soldiers at Bunker Hill were told not to fire until they saw the whites of the enemy soldiers’ eyes, the approach to Biden is the opposite: If you can see the whites of his eyes you’ve waited too long.

It’s a strategy of deterrence. This cycle’s version of it came when Lucy Flores, a former Nevada state assemblywoman, accused the former vice president of touching her shoulders and kissing the back of her head, uninvited, at a 2014 campaign event. “I had never experienced anything so blatantly inappropriate and unnerving before,” Flores, a former board member of the Bernie Sanders-aligned group Our Revolution, wrote on March 29 in the Cut. Biden has a history of public touchy-feely moments, and Flores’ account, as well as the inappropriateness of it, rings consistent. That meant it was only a matter of time before others stepped forward. Sure enough, on March 31 Amy Lappos posted on a Connecticut politics Facebook page that Biden rubbed noses with her unbidden at a 2009 Greenwich fundraiser. She told the Hartford Courant, “It wasn’t sexual, but he did grab me by the head.”

Because Biden has displayed this sort of behavior in public, no one expressed surprise at the recent allegations. “It’s so easy to Google ‘Creepy Biden’ and you get all these compilations of pictures and video evidence of young women and women looking very, very uncomfortable,” Flores said. Rather, they were jarring because it meant after a long career, including eight years in the White House, Democrats were shifting their framing of the incidents from weird-but-harmless to creepy-and-lecherous. For his part, Biden released a video statement April 3 promising to be more mindful of the fact that "social norms have begun to change, they've shifted, and the boundaries of protecting personal space have been reset."

[ Related: Meet the eight women who accused Biden of unwanted touching]

One reason Biden is especially vulnerable to such stories before he launches his campaign is that it’s easier to catch him flatfooted. At the Atlantic, Edward Isaac-Dovere writes about what the response might have been had a Biden campaign been up and running: “Potentially even before the story ran but certainly as soon as it did, reporters covering the campaign closely would have heard from an aide, offering rebuttals and context. Maybe the aide would have pointed out that Flores was a prominent Bernie Sanders supporter in 2016, and a board member of his allied group Our Revolution until resigning last year, or that she spent Saturday morning in El Paso at the kickoff rally for Beto O’Rourke.” Perhaps “a Biden campaign would have fought the publication of the essay in the first place, arguing that it was obviously radioactive politically but impossible to fact-check. Or it might have pointed to pictures that exist online of Biden with his face in [Eva] Longoria’s hair at that same event, and insisted that this was proof he is just a well-meaning nonstop nuzzler.”

Biden should have been acutely aware of this dynamic for many reasons, but one of them is this: It’s a repeat of what happened to him in 2015. He was considering running for president from the White House, but that meant challenging Hillary Clinton. And, in effect, going up against President Obama, who had thrown his weight behind Clinton and warned his veep away from running. Biden was remarkably frank about how this played out in his 2017 memoir, Promise Me, Dad. It is a striking book about juggling his vice presidential responsibilities with his son’s fatal illness.

[ Also read: Biden jokes about allegations he made women uncomfortable]

When Biden eventually took himself out of the running in 2015, the death of his son Beau from brain cancer that May was thought to weigh heavily on the decision. And it did, but not in the way most people thought. Biden himself assumed his son’s health problems meant his family would be against a run for president. But he was wrong. “You’ve got to run. I want you to run,” Beau told him. His other son Hunter agreed. Biden writes: “When I decided was not crucial, my sons told me; they just wanted me to know that they were for it. Hunt kept telling me that of all the potential candidates I was the best prepared and best able to lead the country. But it was the conviction and intensity in Beau’s voice that caught me off guard. At one point he said it was my obligation to run, my duty. Duty was a word Beau Biden did not use lightly.”

Obama, meanwhile, “had been subtly weighing in against — for a variety of reasons. For one thing, the president recognized the media’s increasing appetite for the drama of politics over real policy. The minute I announced I was running for the nomination, Barack and I both knew, coverage in the West Wing would shift from his agenda to my chances. I also believe he had concluded that Hillary Clinton was almost certain to be the nominee, which was good by him.”

[ Related: Biden accuser says she would support him over Trump]

Obama wanted Clinton to carry on his legacy. But to Biden, a presidential race meant far more than a chance at power. It was a way to honor his son. “The mere possibility of a presidential campaign, which Beau wanted, gave us purpose and hope — a way to defy the fates.” Obama urged Biden to meet with the president’s pollster, who then made it clear to Biden that Hillary was more or less invincible. Because Biden and Clinton were so close on the issues and had similar resumes, “Clinton backers sent the signal that they would not stop at voting records and policies if I did get in the race.”

Biden finally got to see what this would look like on Oct. 6, 2015, with a Politico story headlined: “EXCLUSIVE: BIDEN HIMSELF LEAKED WORD OF HIS SON’S DYING WISH.” The new narrative pushed by Biden’s prospective foes was that he was using his deceased son as a political prop. “I should have seen this coming, I guess,” Biden writes. “But the Politico story exceeded even my worst expectations of what the opposition was going to be like. The idea that I would use my son’s death to political advantage was sickening.”

There’s no way to know what would’ve happened had Biden challenged Clinton in 2016. But it’s clear her team understood that Biden was a threat, not a sideshow. And that’s even truer regarding the 2020 race. Polls this early reflect name recognition more than anything, but Biden would start out with a lead: A March poll found he had 31% support, ahead of Sanders at 27%. The bitter irony is that Biden has run for president before — in years when he didn’t have a chance, 1988 and 2008. The 2016 race was tailor-made for someone with blue-collar cred and an ability to take a punch as well as throw one, as Joe Biden can. Arguably 2020 is as well. And yet again, his would-be rivals hope we never find out.

Seth Mandel is executive editor of the Washington Examiner Magazine.