The real lesson from a new book on Biden’s cognitive decline

May 23, 2025

The Rebuild is a newsletter written by senior correspondent Eric Levitz. Read more of his work on a wide range of political and policy issues on our site.

Joe Biden looking down at a presidential debate.

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The real lesson from a new book on Biden's cognitive decline

Biden cost Democrats the 2024 election — but not in the way you think.

Joe Biden lost it before he even won the presidency.

This is the most notable revelation in Original Sin, a new book-length exposé of the Biden White House by Axios's Alex Thompson and CNN's Jake Tapper.

Thompson and Tapper mostly fill in the details of a story we already knew: Biden's cognition declined sharply over his final two years in office, and his core advisers schemed to disguise this reality from donors, Democratic officials, and the public.

But the authors also vindicate those who believed that Biden was already in rough shape before he ever won the presidency. Their book suggests that the former president's cognitive decline began after the tragic death of his son Beau from brain cancer in 2015. By December 2019, Biden was having difficulty remembering the name of his top adviser Mike Donilon, whom he'd worked with for 38 years, and conducting coherent conversations with voters over Zoom.

Original Sin is a sad book, made all the sadder by this week's news that Biden has metastatic prostate cancer. It is also an infuriating read that illuminates the selfishness and self-delusions that led an unwell octogenarian to run for a second presidential term — and a team of sycophantic advisers to conceal his condition from the public (and possibly, even from himself).

This said, Original Sin's core argument — that Biden's reluctance to retire was the primary cause of Democrats' defeat in 2024 — is unconvincing.

Thompson and Tapper argue that had Biden ducked out of the 2024 race in a timely manner, "a competitive primary and caucus process would have produced a stronger Democratic nominee, one who had more experience with debates and taking questions from reporters, one with a more cogent and precise answer as to why they were running, one with time to introduce themselves to the American people."

But the idea that competitive primaries inevitably elevate strong candidates — and/or make mediocre ones better — is undermined by the book's own reporting.

In truth, had Biden dropped out earlier, Democrats plausibly could have done even worse last year. Biden definitely undermined his party. But he made his politically damaging decisions long before the 2024 campaign.

Why a 2024 primary might have been bad for Democrats

Thompson and Tapper's confidence that competitive primaries inevitably yield strong candidates is bizarre. After all, by their own account, the last contested Democratic primary produced a nominee who was incapable of vigorously campaigning, speaking coherently off the cuff, or remembering the names of close friends. Perhaps, Biden was nevertheless the strongest candidate whom Democrats could have possibly mustered in 2024. But if so, that says nothing good about the party's process for picking presidential nominees.

In reality, Biden won the 2020 primary because he had been vice president in 2016. His former post provided him with a degree of name recognition and cachet that no other moderate could match. The vice presidential aura was strong enough to compensate for Biden's dearth of early financing, oratorical incompetence, and stumbles in Iowa, New Hampshire, and Nevada. Thanks largely to his résumé, Biden triumphed in South Carolina, thereby establishing himself as the only viable alternative to Bernie Sanders. The party's center-left swiftly consolidated behind him.

All this has implications for what a 2024 primary would have looked like. Specifically, it suggests that Kamala Harris would have been extremely likely to win such a contest. Harris wasn't merely a former vice president, but a sitting one. She didn't repel donor enthusiasm (as 2020 Biden had) but inspired it.

Counterfactuals are impossible to prove. No one can know with certainty how an open 2024 primary would have gone. Knowing how things turned out in our timeline, I wish such a contest had occurred, on the off chance that it would have produced a different outcome.

But I think Harris would have probably won the 2024 primary. And there's a decent chance she would have emerged from it worse for wear.

A primary could have hurt Harris in 2024

Recall that Harris's 2020 primary campaign rendered her a weaker general election candidate four years later by associating her with unpopular positions on immigration, health care, and much else. Harris likely would have taken a more cautious approach to position-taking in a 2024 primary (as she did during her general election bid). But a contested primary would have forced her to either make high-profile concessions to Democratic interest groups with unpopular demands or else loudly reject those stances. Either way, she was liable to engender bitterness among one part of her coalition or another.

To be clear, this process may have been valuable. In my view, the Biden administration was complicit in Israeli war crimes in Gaza. It's theoretically possible that a contested primary could have led Harris (if not, Biden) to embrace a more adversarial posture toward the Israeli government. But from a purely electoral perspective, elevating divisive intra-Democratic arguments over Gaza, immigration, and other issues in early 2024 probably wouldn't have been to the party's benefit.

All of which is to say, it's plausible that Biden dropping out so late actually redounded to his party's benefit. His tardy departure enabled Harris to immediately focus on appealing to the general electorate. And although Harris's advisers argue that their campaign's truncated timeline hurt them, it's not obvious that this is true. In many cases, presidential nominees have grown more unpopular the longer they've been in the national limelight: Hillary Clinton's favorable rating fell from 64 percent in 2014 to 38 percent in 2016, according to Gallup's polling.

And Harris appears to have suffered from the same basic trend: Her favorable rating was 48.8 percent last September but fell to 46.7 percent by Election Day, in RealClearPolitics' polling average. It's therefore possible that Harris benefitedfrom having a shorter campaign calendar.

Joe Biden still owns Trump's reelection

None of this is meant to exonerate Biden for Donald Trump's reelection. To the contrary, no Democrat is more responsible for that outcome.

It is very difficult for a political party to win another lease on the White House when its president is historically unpopular. And in November 2024, Biden's approval rating sat at 37 percent.

We don't live in a just political universe. Much of Biden's unpopularity was undeserved. Any president who happened to be in power in 2022 was all but certain to preside over inflation, thanks to Covid's aftermath and Russia's invasion of Ukraine. Given the circumstances, Biden's economic record has much to recommend it.

Nevertheless, it remains the case that Biden presided over historically high inflation, which he did virtually nothing to combat. And he also oversaw a historic surge in unauthorized immigration that was politically toxic (despite being economically beneficial), and failed to address majoritarian discontent with record asylum inflows until late in his tenure. Throughout all of this, he saddled Democrats with a standard-bearer who could barely string sentences togetheroff the cuff.

All this meant that, in 2024, Democrats needed a nominee who either had distance from the White House or generational political talent (and ideally, both). By choosing a running mate in 2020 who 1) plainly had presidential ambitions and 2) was a suboptimal standard bearer for Democrats nationally, Biden made it extremely unlikely that his party would have what it needed in last year's race.

Harris ran a respectable campaign. Given Biden's unpopularity, the fact that she came only 230,000 votes short of an Electoral College majority is an achievement. But she had obvious weaknesses as a general election candidate: She was a California liberal who'd taken some deeply unpopular stances in the past, had never won an election outside of a deep blue area, and struggled to speak cogently and confidently in interviews.

That Harris wasn't an ideal Democratic nominee isn't just my opinion — it was also Biden's. His advisers told Tapper and Thompson that his true "original sin" was "picking Kamala Harris because his heart was with Gretchen Whitmer."

It is always irresponsible for a presidential nominee to pick a running mate whom they believe would make a weak national candidate. But it is especially reckless for a 78-year-old presidential nominee to do so. Yet that is what Biden knowingly did in 2020, according to his own inner circle.

The most important lessons of 2024 have little to do with Biden's age

Obviously, one lesson that Democrats should take from the last four years is "it's bad to conceal the rapid mental deterioration of an elderly presidential candidate." But that shouldn't be the party's primary takeaway — both because it's unlikely to be relevant again in the near future and because Biden's age ultimately wasn't Democrats' biggest problem last year. Voters didn't reject Harris because her boss was old, but rather, because they believed that Democrats would do a worse job of managing the economy and immigration, and that Trump was closer to them ideologically than Harris was.

The more pertinent lessons of 2024 are that 1) Democratic presidential nominees must prioritize political talent over sycophancy or identity when selecting running-mates and 2) Democratic administrations must strive to address the electorate's top concerns when in office.

More concretely, Democrats as a party must put distance between themselves and Joe Biden.

The former president accomplished some worthy things. But he also made a lot of ill-advised and deeply selfish decisions. His administration willfully deceived the public while delivering outcomes that voters disliked. Democrats probably would have struggled to nominate an outsider critical of the Biden White House in 2024, even if they'd had an open primary. But they'll have a better opportunity to elevate such a candidate in 2028 — and they should seize it.