Joe Biden used President Trump's denials about intelligence on reported Russian bounties on American soldiers in Afghanistan to question the president's mental ability during a campaign appearance on Tuesday.

What he's saying: "He talks about cognitive capability. He doesn't seem to be cognitively aware of what's going on. He either reads and/or gets briefed on important issues — and then forgets it — or he doesn't think it's necessary that he need to know it."

• "So the idea that somehow he didn't know or isn't being briefed, it is a dereliction of duty if that's the case. And if he was briefed and nothing was done about this, that's a dereliction of duty," the former vice president added.
• "I can hardly wait to compare my cognitive ability with the cognitive ability of the man I am running against."

Why it matters: Biden is trying to turn the tables on the president, who has taunted Biden about misspeaking on the campaign trail.

• The attack comes as the Trump campaign plans to pivot its messaging to focus on the claim that Biden's mental faculties are diminished, Axios' Jonathan Swan reported.
• A growing number of Trump's advisers say their best shot is to convince voters that Biden won't really run the show if elected.

The big picture: Biden took questions from reporters on a range of topics — from coronavirus to his future running mate.

• On his running mate: He said the selection has moved into the "hard vet" phase and noted that "a number of women of color" were under consideration.
• On whether he's been tested for coronavirus: He said he hasn't because he hasn't shown any symptoms, but will be "relatively soon."
• On statues: Biden said "the government has a responsibility to protect" statues of George Washington and Christopher Columbus.
• On his polling lead: "It’s much too early. We have a lot more work to do."