During a speech on Saturday night in front of supporters in Detroit, former president Donald Trump challenged incumbent President Joe Biden's mental capacity, suggesting that Biden needed to take a cognitive test. He also boasted that the White House doctor told him that he is "the healthiest president in history" and that he had already managed to pass a cognitive test conducted by a doctor.

“Doc Ronny Johnson. Does everyone know Ronny Johnson, congressman from Texas? He was the White House doctor, and he said I was the healthiest president, he feels, in history, so I liked him very much indeed immediately," Trump told the crowd.

The former White House doctor and current Congressman from Texas's 13th district is Ronny Jackson, not Johnson, and is considered one of Trump's most vocal supporters in Congress.

Biden's campaign leaders quickly seized on Trump's mistake, releasing a video mocking the former president for his error.