White House coronavirus task force coordinator Deborah Birx said in a memo Monday first obtained by the Washington Post that the U.S. is "entering the most concerning and most deadly phase of this pandemic."Why it matters: In the memo on the eve of the election, Birx contradicts President Trump's repeated claims that the U.S. is "rounding the corner" in the virus fight, as she calls for "much more aggressive action" on the COVID-19 response.Her comments come after NIAID director Anthony Fauci told the Washington Post in an interview Friday that the U.S. was "in for a whole lot of hurt" going into the fall and winter, prompting Trump to suggest he may seek to fire the career civil servant.Driving the news: "This is not about lockdowns — It hasn’t been about lockdowns since March or April," Birx said in the memo, per WashPost and the New York Times."It's about an aggressive balanced approach that is not being implemented."Another report dated Oct. 17 — when Trump held rallies in Michigan and Wisconsin — notes that an increase in hospitalizations and deaths from COVID-19 is "not due to increased testing but broad and ever increasing community spread.""There is an absolute necessity of the Administration to use this moment to ask the American people to wear masks, physical distance and avoid gatherings in both public and private spaces."Worth noting: Unlike Fauci, Birx hasn't publicly clashed with Trump over COVID-19. She's known for taking a more measured approach to gain influence — strategically emphasizing the points Trump wants to hear and playing multiple angles on any given issue, per Axios' Jonathan Swan.The big picture: Cases have been surging to record highs across the country in the past few weeks.More than 231,500 people have died from COVID-19 and nearly 9.3 million have tested positive for the virus, Johns Hopkins data shows.What they're saying: The White House did not immediately respond to Axios' request for comment. But White House spokesperson Alyssa Farah defended the Trump administration's response, saying "[w]e are working around-the-clock to safely treat the virus and ultimately defeat it," according to WashPost.She said the White House has "significantly increased" supplies of personal protective equipment, purchased 150 million COVID-19 tests, distributing them to vulnerable populations, "sent special teams to states and nursing homes with the most cases," develop vaccines and "safely rush therapeutics" to the sick, per WashPost.