Joe Biden, at his first press conference in three months, defended his cognitive ability and said he “can hardly wait” to compare it to President Trump's as the general election matchup heats up.

“I’ve been tested, I’m constantly tested,” Biden said in response to a question from Fox News’ Doug McKelway. “Look, all you’ve got to do is watch me and I can hardly wait to compare my cognitive capability to the cognitive capability of the man I’m running against.”

While Biden’s press conference in Delaware was ostensibly about how he would respond to the coronavirus pandemic, the former vice president also slammed the current White House occupant for his response to reports that Russian intelligence operatives offered to pay bounties to Taliban-linked militants who killed U.S. troops in Afghanistan.

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Biden on Tuesday said it was unimaginable that Trump would not have known about the intelligence, and called into question the president’s cognitive abilities.

"The president talks about cognitive capability, but he is not cognitively aware of what’s going on,” Biden said, reversing a hit the president has used against him.

Biden also called on Congress to investigate the matter and, come Election Day, “for the public to decide whether he is fit for office.”

Trump, 74,  and his campaign have come after Biden, 77, for his frequent gaffes, in May launching a faux "investigative" series that spotlights his numerous verbal miscues on the campaign trail.

“The American people deserve to know the truth behind Joe Biden’s delirious and nonsensical claims on the campaign trail,” Trump campaign communications director Tim Murtaugh said in the video. “When he’s mangling the text of the Declaration of Independence or calling someone a ‘lying, dog-faced pony soldier,’ is he really speaking a language that only he and a select group of others understand?”

Biden, though, opened up in February about his lifelong struggle to overcome stuttering, and his defenders have argued that this sometimes may be a factor in his widely publicized history of stumbling words.

Trump has had his own fair share of verbal miscues, embellished statements and Twitter typos.

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Biden, who Trump has famously labeled “Sleepy Joe,” said in a May interview with Vanity Fair, “I can hardly wait to get onto the stage with Donald Trump,” adding “Trump is a master at laying nicknames on people.”

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The former vice president stressed that “in terms of energy ... I don't have any problem comparing my energy level to Donald Trump who I'm really resisting giving a nickname to.”

Fox News' Paul Steinhauser contributed to this report.