Washington (CNN) Democratic presidential front-runner and former Vice President Joe Biden on Thursday slammed President Donald Trump's July Fourth "Salute to America," saying the event is "designed more to stroke his ego" than celebrate the country.

"I wonder, what will Donald Trump say this evening when he speaks to the nation at an event designed more to stroke his ego than celebrate American ideals?" Biden, whom CNN's Chris Cuomo will sit down with for an exclusive interview that airs Friday, said at a campaign event in Marshalltown, Iowa.

Former vice president and Democratic presidential candidate Joe Biden greets local residents while walking in the Independence Fourth of July parade, Thursday, July 4, 2019, in Independence, Iowa. (AP Photo/Charlie Neibergall)

The candidate asked, "Will he speak to the example America must set to inspire the world? Will he offer a robust defense of the democratic values that have always been our strength in times of crisis?"

"We all know the answer to that -- Donald Trump is incapable of celebrating what makes America great because he doesn't get it."

Trump's event in Washington, billed as a "Salute to America," has prompted controversy for its plans to showcase US military equipment, including M1 Abrams tanks and a military plane flyover. CNN reported earlier this week that some military chiefs have concerns about the politicization of the event, despite Trump's insistence the military was "thrilled" to participate.

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