Joe Biden won big, and it appears that much of his success was fueled by voters’ desire to nominate a safe bet against Donald Trump. A string of last-second dropouts from moderate candidates and endorsements from influential Democrats framed Biden as the only man in the race who could be counted on to end the national emergency that is the Trump era. “The man in the White House today poses an existential threat to this country, to our democracy, to free and fair elections, and we need somebody who can beat him," former 2020 contender Beto O’Rourke said at a campaign rally on Monday. “In Joe Biden we have that man.”

Most worryingly, Biden’s vulnerabilities seem almost perfectly matched to Trump’s strengths. Trump, like Biden, is prone to weird verbal riffs, but he’s alert and light-footed in debate settings, and an able bully; he is adept at convincing Republicans his opponents are corrupt, no matter how self-evidently corrupt he is himself; and his ability to inspire his base to show up at the polls is formidable .

But the fact that Biden has managed to successfully secure the narrative that he’s the surefire solution to Trump is rather miraculous. Hardly a day passes on the campaign trail without a viral video of him appearing to forget the day of the week or confused about whether he’s running for president or Senate —his constant confusion and gaffes have raised serious questions of whether he’s fit to run for office. And Biden’s campaign also bears an eerie resemblance to Clinton’s 2016 run in its vulnerability to perceived corruption and its inability to excite progressives.

It’s evident that many voters share that attitude. A recent YouGov poll found that a majority of Democrats want someone who can win in November, as opposed to someone who shares their views, and according to a Washington Post exit poll, Super Tuesday voters who prized electability supported Biden over Bernie Sanders at a two-to-one rate . This was a vindication of Biden’s campaign strategy, which launched with an ad that made not a single mention of policy but instead presented Biden as a Trump-slayer who could win back “the soul of the nation.”

When Biden speaks on the campaign trail or on the debate stage these days, it’s hard to shake the concern that he is far too old to run for office. The 77-year-old former veep rambles, mumbles and careens down tangents, often sounding like he’s practicing talking points while drifting off to sleep. When responding to a question about the legacy of slavery in education during a debate in September he told the audience to keep “the record player on at night” to help children learn, mentioned that his deceased first wife was a teacher, and started to boast about confronting Venezuelan President Nicolas Maduro—but he didn’t have much to say about reversing systemic racism.

Biden does have some assets as a politician—most notably, his strength with moderate voters—but it’s possible that out of all the frontrunners over the course of the primary season, Biden presents the riskiest gamble of them all.

But one shouldn’t overlook that while Hunter Biden’s appointment was not officially illegal, it was indeed shady . Hunter Biden had no background in gas or Ukrainian affairs, but he received the $50,000 a month gig because of who his father was. Hunter also scored a lucrative deal he was unqualified for in China just after a trip with his father, again profiting off his last name, and signaling a way for other organizations to potentially influence the vice president. That in a sense makes the question of legality somewhat irrelevant—some of the facts of the situation do point to corruption, and will make the aura of scandal harder to dispel.

One of Biden’s biggest liabilities as a nominee is his son Hunter’s past position on the board of Burisma, a Ukrainian energy company. Trump claims that during the Obama years, Biden corruptly sought to pressure Ukraine’s government to fire prosecutor general Viktor Shokin because Biden wanted to protect his son’s job from Shokin’s investigations. This is false : it’s well established that the Obama administration and the West more broadly wanted Shokin out because he was failing in his anti-corruption role.

It should be stressed that the press shouldn't diagnose medical conditions in public figures from afar. But his oldness is tangible in every one of his public appearances, and when he tries to take credit for every important accomplishment of the Obama administration he comes across as a slowly unraveling grandfather telling tall tales about his youth. The problem is voters aren’t as credulous as children gathered around a fireplace—and they’re looking for a compelling leader, not someone who talks wistfully about days gone by.

Trump isn't much younger at 73, and Sanders will be 79 by the time of the election (he also had a heart attack last year). But neither have stumbled in public as often as Biden. Trump is already using the gaffes to sharpen his blade. He has slammed Biden’s errors as “a little scary,” and quipped that Biden would be put “into a home” after winning the White House and allow others to run the government for him. Meanwhile Fox News hosts are pouncing on every slip up and providing it as proof that he’s experiencing cognitive decline .

Puzzlingly, Biden falsely claimed in recent weeks that he was arrested while trying to see anti-apartheid leader Nelson Mandela in South Africa in the 1970s, but eventually admitted it was untrue after he came under scrutiny.

The day after Super Tuesday, Senate Homeland Security Committee Chairman Ron Johnson, a Republican from Wisconsin, announced a new phase of investigation into Hunter's ties to Burisma. Republicans like Johnson didn't make a stink about Burisma when Biden was actually in office and Hunter was actually on the board, making the bad faith here obvious. Clearly, the GOP will use public investigations, reports, and general murmurs of scandal to taint Biden’s name in the eyes of voters. This has all the makings of the Republican hysteria in 2016 over Hillary Clinton’s use of a private email server as Obama’s secretary of state—a scandal that was sufficiently powerful to cause Clinton to lose the razor-close election, according to polling data.

More troubling still is that Biden, flat-footed and sleepy, seems unprepared to handle this line of criticism. When a voter questioned him about Hunter Biden’s entanglements on the campaign trail in December, Biden replied by challenging the man to a push-up contest.

The fact that this is a liability for Biden is ironic of course. It is after all Trump who used his own power to actually pressure Ukraine’s government to act on his behalf, and Trump who has used the presidency to systematically enrich himself and his family in a way that makes the Hunter Biden affair look trivial. But if the New York Times’ fixation on Clinton’s emails in 2016 is any guide, we can count on the political press to obsess over any GOP accusations of impropriety by Biden. If swing voters are convinced both candidates are corrupt, it may persuade just enough to go over to Trump.

Biden has no real inspiration

Biden’s final major category of liability is purposelessness. If you were to try to distill his campaign to a few words it would simply be: “Not Trump.”

This is another feature he shares with Clinton. She too was a longtime party elite whose campaign was defined more by what it was not—Trump or Sanders—than what it was: a patchwork quilt of incremental reforms to the status quo that failed to cohere around a single theme.

Moreover, like Clinton, he lacks the broad charisma or soaring rhetorical power to attract voters to his modest message of “I’ll make things less bad.” That’s why Democratic party elites including Obama took an interest in young upstarts like O’Rourke instead of backing Biden early on in the primary. (Obama has not officially endorsed anyone.) It’s why, despite deep connections to big donors, Biden has regularly struggled to match the fundraising abilities of relatively unknown candidates. It’s why he has struggled to attract big crowds to rallies despite being the best-known candidate in the race. And it’s why so many voters in early primary states were intrigued by Pete Buttigieg, who positioned himself as a moderate but was exceptionally gifted at communicating why he felt it was the best path forward.

So Biden wasn’t the first obvious choice in the eyes of many moderate voters or party elites, and that was reflected in his abysmal performance in the first three primaries. It was his unrivaled ability to garner the votes of Black Democrats in the South that gave him a decisive edge in the centrist lane, and forced the other moderates to consolidate behind him. Biden is of course far less exciting still for progressives. For the first time in the history of modern survey research, a majority of the Democratic Party is made up of self-identified liberals. How will he excite them in the general election when he did things during the primary like promise elite donors at the $34 million penthouse of a hedge fund billionaire that under his presidency, “No one’s standard of living will change, nothing would fundamentally change”?

On paper, Biden’s 2020 policy platform is a nod to Sanders’s influence on the party: it’s more progressive than Clinton’s in 2016, and would be more liberal than anything a Democrat has run on in a general election in decades. But in the past year Biden has also not made a compelling case to liberal Democrats that he’s evolved with the times himself, like when he boasted about working with segregationist senators and declined to truly apologize for touching women inappropriately on dozens of occasions.Many liberals don’t trust him after learning about or remembering his deeply conservative record on everything from the Iraq War to bankruptcy reform to criminal justice.

Lack of enthusiasm has costs: Four million Obama voters simply stayed home instead of voting for Clinton, partly, no doubt, because they were uninspired. The same thing could happen again.

Biden does have strengths that could work for him in a general election. He’s getting strong support from reliable Democratic voting blocs like Black voters, and his strength with moderate voters means that if he can perform slightly better among them than Clinton in the Rust Belt, he could pull off the win. And Sanders is no guarantee of a win himself—we simply have no precedent for understanding how the GOP would mobilize in response to a Jewish, self-identified socialist running for the White House.