Amid Democratic anxiety about the tightness of the presidential race and slippage in support among key voting blocs, Vice President Kamala Harris is increasingly and aggressively painting former President Trump as unprepared and unhinged.

Harris noted that Trump refuses to debate her again, hasn’t disclosed his medical records as she has and backed out of an interview with “60 Minutes.”

“And you have to ask, ‘Why is his staff doing that?’ And it may be because they think he’s just not ready, and unfit and unstable, and should not have that level of transparency for the American people,” Harris said Monday on the online program “Roland Martin Unfiltered.”

Harris planned to further focus on the risk a Trump reelection poses at a rally Tuesday in Pennsylvania and in a new ad that includes Trump’s former national security aides warning about the peril created if Trump wins election in November, according to a senior Harris campaign official granted anonymity to discuss the vice president’s planned messaging.

After weeks of momentum after Harris became the Democratic nominee, polling shows the race has settled into a dead heat, both nationally and in the battleground states that will determine which party wins the White House. Both candidates are laser focused on Pennsylvania, the battleground state with the most electoral votes where Harris is up by less than one percentage point, according to polling aggregator FiveThirtyEight.

Harris has tried to shake up the race with a media blitz in recent days, appearing on traditional shows as well as nontraditional forums aimed at targeting various voter groups. Her campaign announced Monday that she would sit down with Fox News for an interview on Wednesday, the first time she has appeared on the cable channel.

The Trump campaign, which said Harris’ acts reek of desperation, faced flak for statements the former president made about using the military to deal with “the enemy from within.”

On Sunday, he made a campaign stop in Arizona and appeared on Fox News’ “Sunday Morning Futures” show with host Maria Bartiromo.

“The enemy from within, in my opinion, is more dangerous than China, Russia and all these countries,” Trump said on the program, specifically naming Rep. Adam B. Schiff (D-Burbank) as an example. Trump has held a grudge against Schiff since the congressman led an investigation into Russian interference in the 2016 election.

“We have some very bad people. We have some sick people, radical left lunatics,” Trump said. “And it should be very easily handled by, if necessary, by National Guard, or if really necessary, by the military. Because they can’t let that happen.”

Minnesota Gov. Tim Walz, Harris’ running mate, seized upon the comments as he spoke with Wisconsin college students Monday.

“Donald Trump, over the weekend, was talking about using the U.S. Army against people who disagree with him,” Walz said. “This is not some mythical thing out there. He called it the enemy within, and to Donald Trump, anybody who doesn’t agree with him is the enemy.”

Walz said such statements demonstrate the stakes in the election.

“I tell you that because we need to whip his butt and put this guy behind us,” he said.

Harris and Trump both scheduled campaign events Monday in the battleground state of Pennsylvania.

With polls showing Trump having some success in courting Black male voters, the vice president planned to visit a local Black-owned small business for a conversation with Black men before rallying supporters in Erie.

Earlier, she unveiled an “Opportunity Agenda for Black Men” that includes providing fully forgivable loans to entrepreneurs; creating education, training and mentorship programs aimed at increasing job opportunities such as teaching for Black men, and creating a health equity initiative to focus on sickle-cell disease, diabetes and other conditions that disproportionately affect Black men.

The Trump campaign said Harris’ efforts show that her campaign is in peril.

“Kamala Harris is in full-blown desperation mode as she spends the waning days of the campaign attempting to stop the bleeding among voting blocs most traditionally aligned with Democrats,” the campaign said in a statement. “Nowhere is that more evident than in her outreach to Black Americans — voters of whom Democrats have taken advantage for generations.”

Trump also called for Harris to pass a cognitive test, two days after she released a medical report and accompanying letter from her doctor, describing her in “excellent health.” Although it has not released a full medical report, the Trump campaign has issued several physician letters that describe the former president in “excellent health.” Over the weekend, an open letter signed bymore than 230 medical professionals calling for Trump to release his full medical records.

Trump planned to hold a town hall in the Philadelphia suburb of Oaks, just over a week after visiting Butler, Pa., where he was holding a rally in July when an attempted assassin shot at the president, nicking his ear. Trump also visited Scranton and Reading last week.

Trump’s visit follows a weekend stop to the California desert for a rally outside of Coachella. Speaking to thousands of people beneath the scorching sun, Trump railed at California for its high cost of living, homelessness and other struggles. He also repeatedly tied the state’s liberal policies to Harris.

A man was arrested outside the rally Saturday on a gun possession charge, and Riverside County Sheriff Chad Bianco said his deputies had “probably stopped another assassination attempt.” But Vem Miller, 49, told The Times that he brought two guns for self-protection.

Attendees waited for hours during the heat of the day to enter the Calhoun Ranch polo field, just outside the city of Coachella. Many had arrived via shuttle bus from several parking lots in the area. After the rally, hundreds were left stranded for hours waiting for buses to take them back to their cars.