Looking ahead to the first presidential debate scheduled for Tuesday, Sept. 29, President Donald Trump on Sunday reaffirmed his position on the need for former vice president and Democratic candidate Joe Biden to take a drug test.

“No. I’m not joking,” Trump said. “I’m willing to take a drug test, I think he should too.”

President Trump recently tweeted ironically that Biden again declined his proposal for a drug test, “Joe Biden just announced that he will not agree to a Drug Test. Gee, I wonder why?”

According to Breitbart News, at Sunday’s White House press conference, the president mentioned that he had seen previous Democratic debates in which Biden was clearly “out of order,” although he had seen him better during the final primary debate with Democratic Sen. Bernie Sanders (I-Vt.).

President Trump questioned Biden about how he was changing his ways after having had questionable performances in other debates. “People say he was on performance-enhancing drugs; a lot of people have said that, a lot of people have written that.”

Several reporters questioned the sources President Trump referred to and challenged him to clarify his claims.

Amid the discussion about drug testing, former Fox News contributor Dr. David Samadi wrote, “There’s nothing wrong with both of you doing that. It should be done for all candidates running for office.”

Chris Henning, Democratic Central Committee Chair in Greene County, Iowa, who was part of Biden’s caucus when he ran for president in 2008 said, “He’s not good in debates and he comes across like he’s stumbling around, trying to figure out what he’s going to say,” according to The New York Times.

Biden scoffed at the idea of taking a cognitive test on Aug. 5. “Why the hell I would I take a test?” Biden told a reporter who asked him if he had taken a cognitive test as part of the presidential campaign and President Trump’s allegations about his mental state.

“No, I haven’t taken a test. Why the hell would I take a test? Come on, man. That’s like saying to you, ‘Before you got on this program, did you take a test where you’re taking cocaine or not?’ What do you think, huh? Are you a junkie?” Biden responded to CBS News reporter Errol Barnett.

A video that launched President Trump’s campaign on Aug. 17 features a series of compilations of Biden’s public speeches in which he acts strangely or has an erratic verbal performance in 2020, comparing them to strong speeches in 2015 and 2016.