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It’s an ad with a singular goal: to terrify you.

Mostly if you’re an older, white suburban voter, the kind who has been abandoning President Trump in droves and has contributed to his lagging polling both nationwide and in battleground states.

The new ad from the Trump campaign, which simulates a break-in of an older woman’s home and ends with her being attacked, comes amid a sustained advertising assault over the past three weeks from Mr. Trump. The campaign has aired multiple ads depicting a lawless country in chaos and empty police stations, the result of the “defund the police” movement that the ad falsely claims is supported by Joseph R. Biden Jr.

“Clearly what they’re looking to do here is scare the living hell out of seniors,” said Pia Carusone, a Democratic ad maker. But, she said, the ad falls short in the realm of believability. “You’re making the assumption that the voter that you’re hoping to convince is going to relate and think that this could happen. And then you have to make the leap to blame Biden or the Democrats or whoever. And I think it fails that first test.”

Of the $32 million the Trump campaign has spent on television ads over the past 30 days, more than $20.6 million went toward ads that focus solely on the issue of the police. Half of that $32 million has been spent on a singular ad that imagines an empty 911 call center, with an answering service asking callers to select their emergency with a split-screen to violent scenes from the protests.

The Trump digital apparatus has also been running a torrent of ads decrying a country in crisis: “Dangerous MOBS of far-left groups are running through our streets and causing absolute mayhem,” one ad with 308 variations reads, “They are DESTROYING our cities and rioting.” The campaign has spent at least $2 million in the past two months on Facebook ads with similar themes, according to Advertising Analytics, an ad tracking firm.

Hewing to an advertising mantra that has long sought to sow fear and division, dating back to his first ad in 2016 that depicted immigrants as criminals, the ad comes as Mr. Trump has been frantically reaching for a line of attack against Mr. Biden as he trails the former vice president in the polls.

Mr. Biden has said repeatedly that he is not in favor of defunding the police. The quotation from the former vice president selectively edited in the ad fictionalizing a home break-in comes from Mr. Biden’s endorsement video with Ady Barkan, a prominent liberal activist. Asked by Mr. Barkan if “we agree that we can redirect some of the funding,” Mr. Biden replied: “Yes. Absolutely.”

He previously staked out his position early last month, writing in a USA Today op-ed article, “I do not support defunding police.”

But as the Trump campaign has yet to find a line of attack against Mr. Biden that sticks, its unique focus on police reform signals a newfound emphasis in its advertising message.

Polling on the issue has been relatively murky. Early polling in June showed bipartisan support for the protests and their calls for racial justice, but that support has started to wane among Republicans amid constant attacks from Mr. Trump.

And a recent poll from ABC News and The Washington Post found that 55 percent of the country does not support shifting funds away from the police and toward social services. When broken down along party lines, 84 percent of Republicans said they did not support shifting funds, while 60 percent of Democrats said they did.

But polling experts have found that support for shifting resources is often affected by how the question was asked. When it is broadly about taking money away from police departments, public sentiment is often against it. When it is described as reinvesting in mental health, housing or other social services, support grows exponentially.

Even so, as the Trump campaign continues its focus on the police, the coronavirus is still on the top of the country’s mind, especially in regards to November’s election.

“I’d bet a lot that the actress they hired for this is more worried about Covid-19 than a phony threat about cops,” said Stuart Stevens, a Republican strategist and former senior adviser on Mitt Romney’s 2012 presidential campaign. “Ask her how many friends or family she has lost versus how many have been unable to reach 911.”

“Trump is trying to make voters care about their cholesterol count in a knife fight. It isn’t working and it won’t work,” Mr. Stevens said. “More Americans have died in the last three months than any three months in American history. You can’t leave the country. You can’t play sports. You can’t visit your dying relative in the hospital. And Trump really wants to make this about who can protect Americans?”

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Ad of the week: The Masked Biden

It’s one of the more confounding political fights plaguing the country: Despite recommendations from top public health officials that wearing a mask helps reduce the spread of the coronavirus, many people across the country are vehemently against masks, and the breakdown is often related to party affiliation.

Mr. Trump used to eschew masks, a signal his supporters took as further impetus to ignore masks. It wasn’t until today that the president changed course, asking Americans during a news conference to wear a mask.

That stands in stark comparison to Mr. Biden, whose Twitter avatar for months featured the former vice president clad in a black mask. Now, a new ad from the Biden campaign, tracked by a recent speech Mr. Biden gave on the coronavirus, showcases him practicing what he preaches.

The message: The ad begins painting the harsh reality facing the country as the coronavirus continues to spread rapidly, with various news broadcasts quickly cutting across the screen as an excerpt from a speech Mr. Biden gave this year provides the tracking: “Infection rates are now going up in more states than are going down.”

Mr. Biden quickly calls for both unity and sacrifice to fight the virus. “It may be inconvenient, it may be uncomfortable, but it’s the right thing to do as an American,” he says, after listing other virus prevention measures.

But the ad pivots halfway through to Mr. Biden’s case for the presidency, as he pitches himself as a steward who will listen to the guidance of health experts. The visual for his pitch: nearly 30 seconds of consecutive images of Mr. Biden wearing a mask while campaigning.

The takeaway: While the Trump campaign’s messaging varies wildly, the Biden campaign has remained largely focused on fighting the pandemic and the ensuing recovery. Notably, recent ads from the Biden campaign have featured him repeating health guidance, almost as if the ad were a public service announcement on the virus, before switching to his political argument.

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