Amid mounting questions about the president's age, White House press secretary Karine Jean-Pierre criticized Special Counsel Robert Hur on Monday and suggested Biden could do more in one hour than most people could in a full day.
Hur's report on Biden's mishandling of classified documents, released Thursday, recommended no criminal charges against the president.
The investigation, however, laid out how the president struggled to remember key details of his life during interviews with investigators, including when he served as vice president and when his son Beau died.
When a reporter at Monday's press briefing asked Jean-Pierre when they could expect to speak with Biden's doctor, she instead pivoted to a critique of Hur, noting that he is a "Republican prosecutor" and "not a medical doctor."
"It's not for him to speak to. It's just not," she said regarding Hur's assessment of Biden's memory.
Another reporter asked Jean-Pierre what the White House's strategy is to change the perception of a majority of voters who believe Biden is too old to serve as president for another term.
Recent polling has found that Biden's age is a major issue for a majority of not only Americans in general, but also Democrats. A Sunday poll from ABC/Ipsos found that 86% of Americans believe Biden is too old to serve another term, including 73% of Democrats.
"We're gonna continue to lead on leadership," Jean-Pierre replied. "We're going to continue to focus on what this president was able to get done on behalf of the American people."
Jean-Pierre then quoted the words of First Lady Jill Biden when she said Biden "does more in one hour than most people do in a day. His age, with experience and expertise, is an incredible asset, and he proves it every day."
The press secretary continued to defend Biden from renewed scrutiny about his mental acuity throughout the briefing, stressing he is "sharp" and "on top of things."
At one point, Jean-Pierre was asked if Biden is different in private and exhibits more "vigor" than he displays during speeches and interactions with the press.
She claimed that Biden has recently traveled to various states and has tended to engage with the press by answering questions in a "lightweight" and "funny" way.
Jean-Pierre also stated that Biden's physician, Dr. Kevin O'Connor, does not believe a cognitive test is necessary. She said O'Connor believes Biden proves his cognitive ability "every day [in] how he operates and how he thinks."
"I'm just gonna say what Dr. O'Connor said to me about a year ago when [Biden's physical] was released," Jean-Pierre said. "The president proves every day [in] how he operates and how he thinks, by dealing with world leaders, by making difficult decisions on behalf of the American people – whether it's domestic or it's national security. That is how Dr. O'Connor sees it, and that is how I'm going to leave it."
The White House did not return Fox News Digital's request for comment.
Fox News' Anders Hagstrom contributed to this report.