Coronavirus Live Updates: Florida Tops U.S. Record With Over 15,000 New Cases

On both CNN and “Fox News Sunday,” Ms. DeVos reiterated the administration’s stance that the C.D.C. guidelines, which call in-person classes the “highest risk” scenario and recommend a range of safety precautions to keep children and teachers safe, were not mandatory.

That drew a rejoinder from Speaker Nancy Pelosi, who appeared on “State of the Union” after Ms. DeVos and said the C.D.C. guidelines “should be requirements.” “Going back to school presents the biggest risk for the spread of the coronavirus,” Ms. Pelosi said. “They ignore science and they ignore governance in order to make this happen.”

When asked about Mr. Trump’s threats to federal funding, Ms. DeVos gave conflicting answers. She said on Fox that if schools did not reopen, “they shouldn’t get the funds,” while saying on CNN that “there’s no desire to take money away — in fact, we want to see schools open and have been committed to ensuring the resources are there to do that.”

Alberto Carvalho, the superintendent of the Miami-Dade County public schools, the fourth-largest public school system in the country, said on NBC’s “Meet the Press” that federal aid under the stimulus bill enacted in the spring might not be enough to cover the added costs of resuming in-school instruction safely this fall, including providing personal protective equipment like masks and gloves.

“I think for the purchase of P.P.E. and additional disinfection cycles, electrostatic disinfection of schools, alteration of schedules — we may need more bus routes to achieve greater social distancing between the riders — more than likely we will need additional resources earmarked specifically for local governments and school systems,” Mr. Carvalho said.

“We need the community’s collaboration” to get the virus outbreak under control, he said, adding, “We need the science to drive the practice, rather than politics influencing what is legitimately a community concern.”

Gov. Larry Hogan of Maryland, a Republican who has been critical of the Trump administration’s handling of the pandemic, said on “Meet the Press” that he would not be “rushed” into sending children back to school in the fall, despite the threats on federal funding.