U.S. Rep. Ronny Jackson (R-Amarillo) made national headlines this week after calling on President Joe Biden to undergo a cognitive test.

Jackson, who previously served as a White House physician under President Donald Trump, sent a letter on Thursday to President Joe Biden, Physician to the President Kevin O’Connor, and Chief Medical Advisor Anthony Fauci calling on Biden to take a cognitive test and share the results with the American people.

In a statement, Jackson said he believes the American people deserve the results of Biden’s test, noting that President Trump took a cognitive test while Jackson was still serving as Physician to the President.

“The American people deserve to have absolute confidence in their President,” Jackson said. “They deserve to know that he or she can perform the duties demanded of the office, and they deserve to have full transparency on the mental state of their highest elected leader. I would argue that the American people don’t have that confidence in President Biden. When I was Physician to President Donald J. Trump, the liberal media relentlessly pushed a narrative that he needed a cognitive test and that it should be the standard for anyone serving as Commander-in-Chief and Head of State. I administered the Montreal Cognitive Assessment (MOCA) test and President Trump excelled. Given the precedent set and Biden’s clear mental impairment, I believe it is past time he undergo a cognitive test.”

The letter was co-signed by 13 other U.S. Representatives — all of whom are Republicans. Other Texans signing the letter include Reps. Brian Babin, Pat Fallon, and Beth Van Duyne.