FIRST ON FOX: Sen. Lindsey Graham, R-S.C., is urging the White House doctor to convince President Biden to take cognitive and neurological exams and make the results public after his poor debate performance and intensifying scrutiny. 

"Urging the White House Physician to recommend President Biden undergo a cognitive exam is in the best interest of the American people," Graham said in a statement to Fox News Digital. 

Lindsey Graham is asking the White House doctor to tell Biden he should take another neurological exam.  (Getty Images)

"Prominent physicians have recommended the same, and the overwhelming majority of American people have concerns about President Biden’s cognitive fitness. I am hoping President Biden’s physician will see the need and wisdom for this and act accordingly. President Trump has indicated he will take a cognitive exam. President Biden should too." 

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The South Carolina Republican made the request in a letter Friday to Biden's physician, Dr. Kevin O’Connor. 

"The deep public concern with President Biden’s mental acuity is well known," Graham wrote. 

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Biden has reiterated he will stay in the race.   (Chris Kleponis/CNP/Bloomberg via Getty Images)

He referred to Biden's comment from Thursday night suggesting he would take another exam if his doctors said he should. 

"You have an obligation to request that he take such an exam and share the results. Our national security, the welfare of the American people, and our country’s standing in the world demands it," Graham told O'Connor. 

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O'Connor is Biden's doctor.  (Manuel Balce Ceneta/AP)

The letter comes as Democrats continue to turn against the leader of their party, asking him to step aside so someone else can face former President Trump in the November election. 

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Despite calls for him to step down, Biden has claimed repeatedly that he intends to remain in the race, to the chagrin of some in his party. 

Additionally, the increased skepticism of Biden has been followed by a downward trend in the polls for the president as well as down-ballot races being rated more competitive and within reach for Republicans. On Thursday, the nonpartisan political handicapper, the Cook Political Report, shifted a Senate race in Michigan from "Lean Democratic" to "Toss Up," specifically citing the potential for Biden to be a drag on other Democrats. 

The White House did not immediately respond to Fox News Digital's request for comment on Graham's letter.