Some swing voters in Warren, Mich., question Joe Biden's ability to lead the country — calling him a "puppet" who's not "mentally capable of being president" — while admitting they haven't paid much attention to his events, platforms or speeches.

Why it matters: President Trump's branding of Biden is defining him with these voters, particularly Trump's insinuations about senility (though the cognitive swipes have gone both ways between these rivals).

• Trump defended taking a cognitive test in an interview with Fox News' Chris Wallace, and tweeted that Biden "cannot pass the test that I 'aced.''"
• "This president talks about cognitive capability," Biden said at a press conference last month. "He doesn't appear to be cognitively aware of what's going on."

These were the main takeaways from our monthly Engagious/Schlesinger swing-voter focus groups.

• The session last week included nine voters who flipped from Barack Obama in 2012 to Trump in 2016.
• While a focus group is not a statistically significant sample like a poll, the responses show how some voters are thinking and talking about the 2020 election in crucial counties.

The big picture: Amid the coronavirus pandemic, the voters in the focus group were not seeking out details about what Biden is offering as an alternative to Trump.

• Biden's lower profile in mostly virtual events was proving no competition for Trump's provocative attacks and national bully pulpit. Many of the voters couldn't name a single achievement Biden has had in his life.
• While two of them said they plan to vote for Biden over Trump this fall, both said their votes will be anti-Trump — not pro-Biden.

What they're saying: "I just feel that what he’s saying is not making any sense to me," said Sharon T. of Biden's television appearances. She called Biden "a puppet" for wearing a mask in public, suggesting that he was only doing it to be politically correct.

• Many of these voters prioritize the economy as their #1 issue in this election and continue to trust Trump on that issue, saying the economy was doing well before the pandemic.
• In addition to improving the economy and trying to bring more jobs to the U.S., Jeff O. said he's picking Trump because "I don’t think that Biden is mentally capable of being president."
• Matt T. described Biden as "up there in age" and "showing signs of dementia" as well as "a puppet" who is "controlled by a lot of people in the deep state." He went on to define that term as "the lobbyists, the people that have the big money, the people that have influence on a lot of the politicians."

Negative feelings toward Biden were mostly rooted in glimpses of TV highlights and a feeling that Biden "becomes lost in his answers," as one participant put it.

• Shelley D. said she recently watched a YouTube video compilation ofBiden's "blunders" and "all these ridiculous things that come out of his mouth or his stuttering."
• Vicki S., who will vote Biden over Trump because of Trump's handling of the coronavirus, said: "I don’t want either of them. It’s the lesser of two evils in my book.”

The other side: National pollson the relative cognitive abilities of Trump and Biden show that voters overall are more skeptical of Trump's fitness than Biden's.

• A July poll from The Hill/HarrisX found that 56% of respondents think Biden is "mentally fit to be President of the United States," compared to 45% who said the same of Trump.