A group of 14 House Republicans is calling on President Joe Biden to immediately submit to a cognitive test, alleging that his “mental decline and forgetfulness have become more apparent” over the last year and a half.

The lawmakers, led by Rep. Ronny Jackson of Texas, sent a blunt letter Thursday to Biden that began, “We write to you today to express our concern with your current cognitive state.”

The other signatories of the letter were Reps. Bob Gibbs, R-Ohio, Jeff Duncan, R-S.C., Andy Harris, R-Md., Brian Babin, R-Texas, Jody Hice, R-Ga., Claudia Tenney, R-N.Y., W. Gregory Steube, R-Fla., Tom Tiffany, R-Wis., Kat Cammack, R-Fla., Jerry L. Carl, R-Ala., Pat Fallon, R-Texas, Diana Harshbarger, R-Tenn., and Beth Van Duyne, R-Texas.

The members of wrote that that former President Donald Trump passed a cognitive test in 2018 and argued that Biden and all future presidents should follow in his footsteps.

“The American people should have absolute confidence in their President,” they wrote. “They deserve to know that he or she can perform the duties of Head of State and Commander in Chief.”

Jackson played a prominent role in Trump’s 2018 cognitive test. The congressman was then the White House physician. He declared at a White House press briefing afterward that Trump did “exceedingly well” on the assessment and was mentally “very sharp” and “very intact.” 

In their letter, the House Republicans cited a number of examples of instances they believe exhibited Biden’s diminishing mental fitness. Among them were forgetting or mispronouncing names in speeches, mixing up Air Force One and Air Force Two in public comments, misquoting the first line of the Declaration of Independence and saying during a speech in Texas, “What am I doing here?” 

“Unfortunately, your forgetfulness and cognitive difficulties have been prominently on display over the past year,” the lawmakers wrote.

The White House did not respond to an email from Spectrum News seeking comment about the Republicans’ letter.

At 78, Biden is the oldest president to hold office.

Jackson is amplifying one of Trump’s go-to attacks on Biden during the presidential election. Trump repeatedly raised questions about Biden’s mental fitness to be president.

In July 2020, Trump said he had “very recently” taken another cognitive test at Walter Reed National Military Medical Center and “aced it,” claiming doctors marveled at his performance.

In a separate interview with Fox’s Chris Wallace, Trump boasted about being able to repeat five words — “person,” “woman,” “man,” “camera,” “TV” — given to him earlier in the assessment.

The test, called the Montreal Cognitive Assessment, is designed to detect mild cognitive impairment and Alzheimer's disease.

Trump challenged Biden to take the same test but Biden declined, saying at one point, “Why the hell would I take a test?” 

The White House said last month that Biden will undergo a regular physical exam later this year. In the last public update on Biden’s health, in December 2019, his physician said he was a "healthy, vigorous” and “fit to successfully execute the duties of the Presidency."

The Associated Press contributed to this report.