Former President Donald Trump mocked the DeSantis campaign on Monday after the campaign’s continued attacks on Trump’s mental health fell flat.

For weeks, the DeSantis campaign has attempted to switch tactics, questioning Trump’s mental health much in the same way that many question President Biden’s mental fitness. One of their main attacks has involved pointing out when Trump uses the word “Obama” instead of “Biden” — something Trump said he has purposely done to indicate that others may be controlling Biden’s presidency behind the scenes.

“Whenever I sarcastically insert the name Obama for Biden as an indication that others may actually be having a very big influence in running our Country, Ron DeSanctimonious and his failing campaign apparatus, together with the Democrat’s Radical Left ‘Disinformation Machine,’ go wild saying that ‘Trump doesn’t know the name of our President, (CROOKED!) Joe Biden. He must be cognitively impaired,'” Trump began in a Truth Social post Monday morning, making it clear that he knows “both names very well” and “never” mixes them up.

Trump added that they are destroying the country and highlighted the fact that he took a “cognitive test as part of my Physical Exam, and ACED it.”

“Also ACED (a perfect score!) one taken while in the White House,” Trump continued, demanding Biden, now 81, do the same.

“Biden should take one so we can determine why he wants Open Borders, No Energy Independence, A Woke Military, High Inflation, No Voter I.D., Men playing In Women’s Sports, Only Electric Cars & Trucks, A Weaponized DOJ/FBI, and so many other CRAZY things!!!” Trump exclaimed.

Trump’s remark comes on the heels of  the DeSantis War Room touting a running list of Trump’s so-called “fumbles,” which include using “Obama” in lieu of “Biden.”

The DeSantis campaign’s continued attacks come as Trump continues to trounce the governor in poll after poll, continuing to lead him in South Carolina, New Hampshire, and Iowa by double digits, despite great efforts by the DeSantis campaign to boost his standing in the polls. But even an endorsement from Iowa Gov. Kim Reynolds did little to nothing to move the needle in DeSantis’s direction in the Hawkeye State.

WATCH: Exclusive — Trump on DeSantis: ‘He’s Crashing Badly,’ Will Be ‘Superseded’ in Second Place

That aside, Trump used Biden’s birthday to share the letter from his personal physician — Dr. Bruce Aronwald, D.O., of Morristown Medical Group — which states in part, “I am pleased to report that President Trump’s overall health is excellent. His physical exams were well within the normal range and his cognitive exams were exceptional.”

“It is my opinion that President Trump is in excellent health, and with his continued interest in preventive health monitoring and maintenance, he will continue to enjoy a healthy active lifestyle for years to come,” the physician added: