Calling it "one of the worst policy mistakes any president has made in our history," Joe Biden's campaign is intensifying its criticism of President Trump's leadership of the government's response to the coronavirus by focusing on four key areas of concern.

A memo obtained by CBS News and sent to campaign allies and leading party activists outlines how the Biden team plans to continue sowing doubts about the president's leadership. The sharper focus comes as Biden in recent days has said that Mr. Trump "has no interest in solving this problem and saving lives" and has outlined a series of specific steps he would have taken to better organize a federal response to the pandemic.

The sharpened attacks come amid growing calls from Democratic Party activists and thought leaders for Biden to figure out a better, more prominent way to speak out regularly about the government response to the pandemic and other issues in order to maintain his advantage over the president. The former vice president has spent considerable time in front of cameras set up in his Wilmington, Delaware, home for television and social media interviews with inquisitors ranging from Showtime's "Desus and Mero," to "The Late Late Show" host James Corden, to his college-aged granddaughter, Finnegan.

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Biden maintains a single-digit advantage over the president in national polling released in recent days, wide leads among historically supportive demographic groups and a narrow edge in key industrial swing states, including Michigan and Pennsylvania, that Democrats need to win back in order to win the White House.

But there are signs of concern for his campaign specifically on coronavirus, the issue currently dominating American thinking. An NBC/Wall Street Journal poll released this week found that just 36% of respondents said they generally trust what the president is saying when it comes to the coronavirus; 52% don't trust him. But, Biden fares worse: just 26% trust what he says about the pandemic, 29% don't trust him and 42% are not aware of what he has said about the pandemic or don't have an opinion.

The memo says that the campaign plans to focus on "four critical errors" made by Mr. Trump. First, "The Chinese government" and how the president praised Xi Jinping without fighting "anywhere near hard enough to get the facts." Second, "Cover-up" and how Mr. Trump "denied and downplayed the danger." Third, "Chaos" and how the White House's "mismanaged response did not get us ready. Finally, "Corporate favoritism" and how Mr. Trump delayed enacting the Defense Production Act to order industries to begin producing medical supplies and testing equipment and how federal relief "favors big companies and those with special access over small businesses."

Biden says he would have made faster use of the DPA and has called for establishing a federal pandemic board to help state governors determine how best to test residents for the virus.

News of the memo was first reported by Axios.

Read the full memo here: