Vice President Kamala Harris made a sweeping push on Monday to energize Black voters, among whom she faces slipping support, unveiling a plan to bolster the finances of Black men, appearing in interviews with two Black media outlets and releasing a pair of ads in battleground states targeted to that crucial voting group.

Taken together, Ms. Harris’s blitz put forward a broad argument that her administration would deliver meaningful policy changes for Black Americans and that former President Donald J. Trump was making empty promises that contradict his history of racist remarks.

“There is a very big difference between Donald Trump and how I will be president of the United States,” she said, citing his false claims about Haitian immigrants in Ohio and detailing her plans to cut taxes for the middle class during an appearance on The Shade Room, a digital entertainment publication with more than 29 million followers on Instagram.

“And I cannot impress upon people enough that this is somebody — Donald Trump — who intends to take us backward,” she added.

The Harris campaign is facing pressure to shore up support from voters of color, who are normally reliable Democratic constituencies, and from Black men in particular. Polls show that Ms. Harris is receiving significantly lower support from Black men than President Biden did in 2020. The slip from Mr. Biden’s 2020 numbers among that voting bloc is striking: 70 percent said they would vote for Ms. Harris in November, down from Mr. Biden’s 85 percent in 2020.

In her interview with Justin Carter of The Shade Room, Ms. Harris acknowledged the challenge, saying: “Black men are no different from anybody else. They expect that you have to earn their vote.”