Former White House Doctor Ronny Jackson on Tuesday, Feb. 25, suggested that Democrat presidential candidate Joe Biden may need to undergo cognitive testing.

“Remember the cognitive test I gave @realDonaldTrump? The one he aced! Sounds like somebody else might need some testing done!! Scary!!” Jackson tweeted.

Jackson, who served both former President Barack Obama and President Donald Trump as White House physician from 2013 to 2018, made the remarks in response to Biden saying on Monday night that he was running for the U.S. Senate.

“Where I come from, you don’t go very far unless you ask,” Biden said. “My name’s Joe Biden. I’m a Democratic candidate for the United State’s Senate. Look me over. If you like what you see, help out. If not, vote for the other Biden. Give me a look though, okay?”

This is not the first time Biden has made mental errors while on the campaign trail. The former vice president, 77,  at a CNN town hall in Las Vegas, Nevada, on Feb. 19,  told voters that he would not seek a second term as president if his health declines.

“I’m in pretty good health, but, look, I guarantee you this: If anything changed in my health, making it incapable for me to fully exert all the energy and mental acuity that was needed to be done, then I give you my word: I would not run again,” Biden said.

Biden primary competitors Sen. Bernie Sanders (I-Vt.) and former New York City Mayor Michael Bloomberg are both 78 and Sen. Elizabeth Warren (D-Mass.) is 70.

Biden saw his national polling numbers plummet this month after his fourth place finish in the Feb. 3 Iowa caucuses and distant second place finish in the Feb. 22 Nevada caucuses.

On the debate stage Tuesday night, Biden while attacking Sanders over his record on gun control, grossly overstated the number of gun deaths since 2007, reported Fox News.

“Imagine if I stood here and said we give immunity to drug companies, we give immunity to tobacco companies. That has caused carnage on our streets,” Biden said. “150 million people have been killed since 2007 when Bernie voted to exempt the gun manufacturers from liability, more than all the wars, including Vietnam from that point on.”

However, in reality, the number is far lower than Biden’s claim. There were around 350,000 firearm deaths in United States from 2007 to 2017, which includes both violent firearm deaths and unintentional or accidental deaths, according to the Fox News.