Biden's age and health concern Americans. But, numbers show voters worry about Trump, too

Millions of Americans are “very concerned” about the health and fitness of President Joe Biden as well as presumptive Republican nominee Donald Trump , according to a new analysis by Resonate .

Those concerns, though, will likely weigh more heavily on as many as 5 million independent voters who might lean toward Biden in November, the AI-powered consumer data and intelligence company wrote Thursday.

Resonate released a report exclusively to USA TODAY shortly before Biden held a press conference where he hoped to persuade more Americans that his debate performance two weeks ago was an anomaly. Trump is just days away from accepting the Republican nomination at the national convention .

Joe Biden is old. So is Donald Trump. So are millions of other American workers

Worries about Trump's and Biden's fitness rise with Americans' ages

Resonate's process is unlike typical polling that extrapolates the pulse of American voters from a few hundred or thousand responses. The company uses its AI-modeling system to develop insights on about 250 million people. It's expansive data set includes more than 4 trillion bits of information that create a detailed profile including everything from demographics and psychographics to why people make the decisions they do.

"Resonate's advanced technology delivers the most comprehensive, updated understanding of any audience at scale," Ericka McCoy, Resonate's chief marketing officer, said in an email. "We have successfully predicted the last two presidential elections, down to key states like Michigan and Florida."

It's not my candidate. Its yours.

Perhaps not surprisingly Republicans and Democrats are split on which candidate's health and fitness we should worry about. If you voted for Biden in 2020, you're mostly likely "very concerned" about Trump's health and vice versa.

Also, not surprisingly: Even intense health and fitness concerns wouldn't move the needle for either Democrats or Republicans, Resonate predicts. Independent votes, though, might be swayed for and against both candidates.

Resonate estimates 37 million more voters are concerned about Biden's health than Trump's, which the analysis says "poses a significant risk for Biden, particularly among independent and third-party voters."

How much either candidate's health and fitness concerns will shift voters' choices in November may be up for debate, but traditional polling also suggests there's been a slight shift.

Following Biden's faltering debate performance, Trump took a lead – although not decisive – in a USA TODAY/Suffolk University Poll of 1,000 registered voters conducted by landline and cell phone.

In a similar USA TODAY/Suffolk poll taken in May, the candidates were tied with 37% of the vote . Following the June 27 debate, the June 28-June 30 poll tilted in Trump's favor 41-38.

Another finding from that poll raised redder flags for Biden and, perhaps, the election: 41% of Democrats said they wanted Biden replaced at the top of the Democratic ticket.

Contributing: Susan Page, Rachel Barber

This article originally appeared on USA TODAY: Biden's age and health concern Americans. But, numbers show voters worry about Trump, too