More than 60 Republican congressmen have sent a letter to US President Joe Biden demanding that he takes a cognitive test or withdraw from the 2024 presidential race, Fox News reports.

The letter says that in light of Biden's announcement of 2024 presidential reelection campaign, they are concerned about his "current cognitive state and ability to serve another term as President."

"We believe that, regardless of gender, age, or political party, all Presidents should document and demonstrate sound mental abilities," GOP lawmakers wrote.

"While you have undergone two physical exams during your presidency, one on November 19, 2021, and another on February 16, 2023, there is no indication you have had any cognitive assessment, or if you have, such results were concealed from the public," the lawmakers continued.

"When you first announced your bid to run in the 2020 presidential election, questions and concerns were raised surrounding your cognitive abilities. Those concerns have only increased because your mental decline and forgetfulness have become more apparent since you were elected. Over the past two years, public appearances where you shuffle your feet, trip when you walk, slur your words, forget names, lose your train of thought, and appear momentarily confused have become more of a common occurrence," congressmen say.