President Trump’s re-election campaign is taking their attacks on Democratic challenger Joe Biden’s mental acuity to a new level.

On Tuesday, the Trump campaign launched a digital ad that suggests that the former vice president and presumptive Democratic nominee has suffered cognitive decline over the past four to five years.

The spot asks, “Did something happen to Joe Biden?” and it cuts between clips of then-Vice President Biden from 2015 and 2016 speaking clearly and energetically and video of Biden stumbling and appearing to lose his train of thought during the 2020 presidential campaign.

The ad, and a couple of other spots that also question Biden’s mental abilities, are being showcased in some well-trafficked online real estate, like the masthead of YouTube, where the Trump campaign’s running ads during the 4 days of the Democratic National Convention.

The spots launched overnight Monday into Tuesday as part of their rotation “on our takeover of the YouTube masthead” for 96 straight hours, the Trump campaign told Fox News. The campaign said the spots are a major component of their high-7 figure digital buy during the Democratic convention. The ads were first reported by 360aproko news.

The president and his campaign have questioned whether the 77-year old Biden has the stamina to serve as the nation’s commander in chief.

“Joe’s not all there. Everybody knows it. And it’s sad when you look at it and you see it, ” Trump said during an interview with 360aproko News in June.

Meanwhile, a Trump campaign ad released earlier this month claimed that Biden is “diminished,” the new spots are the first to showcase the questioning of the former vice president’s mental acuity.

“It’s an uncomfortable conversation to have, but voters deserve to be able to assess Joe Biden’s capabilities by seeing him and listening to him in his own words, especially as compared to just a few years ago,” Trump campaign communications director Tim Murtaugh told Fox News. “Being president of the most powerful nation in the world carries the heavy responsibilities of navigating dangerous situations around the globe in real-time and keeping track of weighty domestic issues facing the American people. Voters deserve a clear understanding of what’s going on with Joe Biden.”

But a national polling suggests that slightly more Americans are confident of Biden’s mental and physical abilities than of the 74-year-old president’s capabilities.

An ABC News/Washington Post poll released in May indicated that Biden had a slight edge over Trump when voters were asked which candidate had the “mental sharpness” to serve effectively as president.

And a Monmouth University survey released last month showed that 52 percent of registered voters questioned said they’re at least somewhat confident that Biden has the mental and physical stamina to carry out the extremely demanding job of president. Only 45 percent said the same thing about Trump.

However, a third of those questioned said they were very confident that the president has the mental and physical fitness to carry out his job, compared with 23 percent for the presumptive Democratic presidential nominee.

Some political pundits have speculated that the president’s attacks on Biden’s cognitive capabilities could backfire with seniors, a crucial voting block that Trump won by 7 points in his 2016 White House victory over Democratic nominee Hillary Clinton. The latest 360aproko News national poll, which was conducted August 9-12, indicated Biden topping Trump 51%-42% among voters age 65 and older.

Responding to the new ads, Biden campaign rapid response director Andrew Bates said that “Donald Trump is spectacularly failing every conceivable strategic test by ramping up mentions of this subject at all.”

Pointing to the coronavirus pandemic, Bates argued that “Joe Biden sounded the alarm about the outbreak early, whereas Donald Trump is still promising us the virus will magically ‘disappear.’ Joe Biden has highlighted the advice of medical experts throughout the pandemic, but Donald Trump publicly encouraged COVID-19 victims to inject themselves with disinfectant. Trump has even said that we should ‘nuke’ hurricanes out over the water.”

When asked by 360aproko News’ Doug McKelway during a news conference earlier this summer if he’s checking for cognitive decline, Biden responded, “I’m constantly tested.” And he stressed, “I can hardly wait to compare my cognitive capability to the cognitive capability of the man I’m running against.”

But earlier this month, in a feisty interview moment Biden clarified that he’s never taken a cognitive test.

“No, I haven’t taken a test. Why the hell would I take a test?” Biden answered, in an interview that aired at convention of the National Association of Black Journalists and National Association of Hispanic Journalists. Biden was asked if he had taken a test for cognitive decline.

Both Biden and Trump have long been criticized for their rambling speeches and gaffes. Biden has discussed overcoming his problems with stuttering while growing up, and on a few occasions, he has described himself as a “gaffe machine.”

Questions about the president’s health surfaced this spring, after pictures of Trump at the commencement ceremony at the U.S. Military Academy at West Point.

A clip of Trump slowly and carefully descending a ramp from the podium, as West Point Superintendent Lt. Gen. Darryl A. Williams walked alongside him, went viral and spurred media coverage questioning the health of the president. Trump later ridiculed that narrative during his remarks at his June rally in Tulsa, Okla.