More than 50 Republicans call for Biden to take cognitive test, amid Dem concerns about president's age

More than 50 House Republicans on Wednesday are calling for President Biden to take a cognitive test, as the president's opponents, and even some allies, question his fitness for the job at age 79. 

Fifty-four Republicans signed the letter, addressed to President Biden, which was led by Rep. Ronny Jackson, R-Texas. That's up from 13 co-signers on a similar letter Jackson led in June 2021, and 37 co-signers on a letter in February. 

The latest letter also includes key members of House Republican leadership, including Republican Study Committee Chairman Jim Banks, R-Ind., Conference Chair Elise Stefanik, R-N.Y., and Conference Vice Chair Mike Johnson, R-La.

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"We again write to you to express concern with your current cognitive state and to urge you to submit to a cognitive test immediately. We believe that, regardless of gender, age, or political party, all Presidents should follow the example set by former President Trump to document and demonstrate sound mental abilities," the letter says. 

"While you have largely brushed aside these assertions as partisan political attacks, the left-leaning New York Times recently published an article outlining all of this in great detail," the letter continues. "According to The New York Times, the increased scrutiny surrounding your cognitive state has been fueled by your recent public appearances."

Jackson, a former White House physician himself, has been the loudest voice in the GOP push for Biden to take a cognitive test. The White House dismisses the effort as a publicity stunt. 

"I honestly don’t care about Ronny Jackson’s ‘look at me’ routine," White House spokesman Andrew Bates told Fox News earlier this year in response to Jackson pushing for a presidential cognitive test. "But if y’all get any mail from Nick Riviera, please don’t be a stranger."

Bates was referring to "The Simpsons" character Dr. Nick Riviera — better known as Dr. Nick — who is a quack medical doctor with shady credentials.

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The New York Times story referenced by Jackson's letter cites a poll showing that most Democrats do not want Biden to be the party's nominee in 2024. The most prominent reason for that, according to the poll: his age. 

Meanwhile, Politico reported last month that Democrats are privately raising concerns about Biden's age, as he approaches octogenarian status. And The New York Times reported that Biden's age is a "deep concern" for Democratic officials. 

Biden also often makes verbal gaffes, ranging from the inane, like appearing to try to shake hands with a person who is not there, to the severe, like saying the U.S. may tolerate a "minor incursion" from Russia into Ukraine. The White House has often needed to walk back the president's statements right after he makes them. 

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"The American people should have absolute confidence in their President, knowing that he or she can perform their duties as Head of State and Commander in Chief," the letter, which cites a cognitive test former President Donald Trump took while in office, says. "They deserve full transparency on the mental capabilities of their highest elected leader"

Jackson told Fox News Digital that he sees increasing support for his latest letter on Biden's mental state as a vindication for his earlier focus on the issue. 

"I have long said there would come a time when I was not the only one discussing Joe Biden’s cognitive decline. That time is now," he said. "This is not a political issue, it’s common sense. If Joe Biden is confident in his ability to excel at a cognitive test the way President Trump did, he can easily put his fellow Democrats’ fears to rest with this one simple test."

Fox News' Houston Keene contributed to this report.