The White House has blasted a report from a Department of Justice special counsel that suggested President Joe Biden was suffering memory lapses, and Vice-President Kamala Harris called the report "clearly politically motivated".
The report from special counsel Robert Hur, a former US attorney in Maryland during Republican Donald Trump's administration, has prompted an election-year brawl and renewed questions about Biden's advanced age.
This week Biden, 81, mixed up the names of several world leaders.
Ian Sams, spokesman for the White House legal counsel's office, joined press secretary Karine Jean-Pierre in the White House briefing room on Friday to criticise Hur's report and raise questions about his motivation.
Hur said in a report released on Thursday that he chose not to bring criminal charges following a 15-month investigation into Biden's handling of classified documents because the president co-operated.
Hur said Biden would be difficult to convict and described him as a "well-meaning, elderly man with a poor memory" who was not able to recall to investigators when his son, Beau Biden, died.
"We don't think that part of the report lives in reality," Jean-Pierre said.
"We just reject that this is true," Sams said.
Harris rushed to Biden's defence when asked about the issue after a White House appearance.
"The way that the president's demeanour in that report was characterised could not be more wrong on the facts and (is) clearly politically motivated," she said, according to a pool report.
Biden and Attorney-General Merrick Garland have sought to present the Department of Justice as independent from the White House after Trump put pressure on the department to shut down a probe into Russia's role in the 2016 election.
Biden said Thursday evening he still believed special counsels should have been appointed to investigate whether he or Trump had mishandled classified documents.
However, Sams suggested Hur, a Republican, might have been influenced by politics.
"We're in a very pressurised political environment. And when you are the first special counsel in history not to indict anybody, there is pressure to criticise and to make, you know, statements that may be and otherwise you wouldn't make," Sams said.
Sams said the special counsel's comment that Biden could not remember the date of his son's death was "really out of bounds".
Biden reacted furiously to Hur's comment about his son, saying "how the hell dare he" bring this up.
Biden's son Beau Biden died in 2015 after battling brain cancer.
The president regularly invokes the death of his son when consoling relatives of service members who died in action or victims of gun violence, and visits his grave site on the May 30 anniversary of his death.
Biden gave the interviews that the special counsel report was based on October 8 and 9 as he organised the US response to the October 7 Hamas attack on Israel.
Jean-Pierre said Biden's physician during his physical exam last year opted not to give Biden a cognitive test because he clearly was able to handle the rigours of being president.
Trump, 77, the frontrunner for the Republican presidential nomination, has misidentified people as well, recently confusing Republican opponent Nikki Haley with Nancy Pelosi, the California Democrat who was speaker of the House of Representatives when he was in power.
As well as a classified documents investigation, Trump faces lawsuits, charges, trials and fines related to his attempts to overturn Biden's 2020 election win, business dealings and sexual abuse.