It was a political grenade disguised as a 345-page report.
The pyrotechnics were delivered on Thursday afternoon in the findings of special counsel Robert Hur’s investigation into Joe Biden’s handling of classified documents after he left the vice-presidency in 2017.
The top-line conclusion was that the president would not face criminal charges for his actions, despite evidence that he had “wilfully retained and disclosed classified materials… when he was a private citizen”.
The bottom line was much more damaging. Among the reasons Mr Hur listed for why he had decided not to prosecute the 81-year-old president was because he would likely be a sympathetic figure to a jury who would view him as a “well-meaning, elderly man with a poor memory”.
Issues about Joe Biden’s age and competency to serve another four years in office have been simmering for practically as long as Mr Biden has been in the White House, so this latest finding will provide fuel for Republican attacks and stoking concerns among some Democrats that the president is not up to the task.
It is a narrative that the Biden campaign has been desperately trying to confront, said Chris Borick, the director of the Muhlenberg College Institute of Public Opinion.
“The polling, over and over, we see data points that suggest it is his largest liability into this election that voters think he’s simply too old to run,” he says.
It’s no surprise, then, that the Hur report prompted the White House to launch a furious counter-offensive that included the president holding an impromptu press conference, where he asserted that his memory was “just fine”.
“I know what the hell I’m doing,” he said.
What’s more, the special counsel presented specific evidence to back up this assertion. He wrote that during two days of interviews, Mr Biden had frequently been unable to recall details relevant to the investigation. More than that, Mr Hur recounted, he had struggled to recall which years he had been vice-president and when his oldest son, Beau Biden, had died of cancer.
It was this last claim that prompted an angry response from the president during his press conference at the White House on Thursday evening.
“How in the hell he dare raise that?” the president said.
The press conference itself could lend more fuel to the attacks on Mr Biden, however, as the president answered a question about the Gaza War by referring to Egyptian President Mohamed al-Sisi as the president of Mexico.
That stumble, not unlike other verbal miscues by Mr Biden in recent days, exposes the scope of the challenge facing his re-election effort. The best way for the president to address concerns about his age is to run a vigorous campaign and increase his public exposure. But every attempt comes with the risk of actions or evidence that feed existing concerns.
The White House has made other efforts to defuse the potency of the Hur report. Mr Biden’s personal lawyer, Richard Sauber, tried to convince the special counsel to drop references to Mr Biden’s mental acuity and mental lapses, writing in a letter that such language was not “accurate or appropriate”.
Mr Biden also noted that he had given his two days of testimony to the special counsel shortly after the 7 October Hamas attack on Israel – while he was “in the middle of handling an international crisis”, he said.
Other Biden allies have pushed back on Mr Hur’s impartiality, pointing out that he was appointed to a US attorney office by Donald Trump in 2017. It was Biden Attorney General Merrick Garland who selected Mr Hur as special counsel, however.
The Biden team has also been quick to pounce on the verbal missteps of his likely November opponent, 77-year-old Donald Trump. The former president recently confused his primary opponent Nikki Haley with former Democratic Speaker of the House Nancy Pelosi and referred to Hungarian Prime Minister Viktor Orban as the leader of Turkey.
The best case for the White House may be that this particular grenade exploded in February, a full nine months from election day.
Larry Sabato, the director for the Center for Politics at the University of Virginia, says concerns about Mr Biden’s age are already essentially baked into the race, making the report damaging but not fatal.
The public “will look at it, and will raise one eyebrow, not both”, he says. “Because in a way, people already knew this. Even if you casually watch five minutes of a speech he’s giving, you already know this,” he says.
When American voters finally head to the polls, the assertions contained in a special counsel report that ultimately declined to find Mr Biden criminally culpable will be of less concern than issues like the economy and abortion.
The worst-case scenario, on the other hand, is that this is just the start of a cavalcade of evidence undermining the president on one of his weakest attributes. And the arrow of time only points one way.
The president isn’t getting any younger.