Dr. Anthony Fauci says he's concerned about the Midwest reopening, noting that hard-hit South and West states like Florida, Texas, Arizona and California look like "they may be cresting and coming back down."

States like Ohio, Indiana, Tennessee and Kentucky are "starting to have" a "very early indication" of rising COVID-19 positivity rates – a "surefire sign that you’ve got to be really careful," Fauci told ABC News chief anchor George Stephanopoulos on "Good Morning America" Tuesday.

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The director of the National Institute of Allergy and Infectious Diseases urged states to reopen in a manner consistent with the federal government’s guidelines for reopening.

PHOTO: Pedestrians wear masks as they walk in front of a sign reminding the public to take steps to stop the spread of coronavirus, July 23, 2020, in Glendale, Calif.
Chris Pizzello/AP
Pedestrians wear masks as they walk in front of a sign reminding the public to take steps to stop the spread of coronavirus, July 23, 2020, in Glendale, Calif.

If the guidelines are followed, Fauci said, "I think we can prevent the surges that we’ve seen in the southern states, because we just can’t afford, yet again, another surge."

Asked if the U.S. needs a coordinated, national reopening strategy, Fauci pointed to the guidelines the federal government had already released and asked states to "rethink what happens when you don’t adhere to that."

PHOTO: A health care worker uses a picture to show a person how to use a nasal swab for a self administered test at the new federally funded COVID-19 testing site at the Miami-Dade County Auditorium on July 23, 2020, in Miami.
Joe Raedle/Getty Images
A health care worker uses a picture to show a person how to use a nasal swab for a self administered test at the new federally funded COVID-19 testing site at the Miami-Dade County Auditorium on July 23, 2020, in Miami.

Fauci also responded to a claim retweeted by President Donald Trump that said the CDC and doctors are "lying."

Trump two weeks ago retweeted a post from former "Wheel of Fortune" host and conservative commentator Chuck Woolery, who wrote, "Everyone is lying. The CDC, Media, Democrats, our Doctors, not all but most, that we are told to trust. I think it's all about the election and keeping the economy from coming back, which is about the election."

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"I don't know how to address that. I'm just going to certainly continue doing my job," Fauci said. "You know, I don't tweet. I don't even read them."

"This is what I do, this is what I've been trained for my entire professional life, and I'll continue to do it," Fauci said. "I have not been misleading the American public under any circumstances.”

Fauci also addressed hydroxychloroquine, the drug Trump self-administered that has since had its emergency authorization revoked by the FDA. Trump on Monday night tweeted his praises of the hydroxychloroquine, but Fauci told "GMA," "The overwhelming, prevailing clinical trials ... have indicated that it is not effective in coronavirus disease."

This report was featured in the Tuesday, July 28, 2020, episode of “Start Here,” ABC News’ daily news podcast.

"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.