A day after vowing to publicly pressure states to fully open their schools despite the Coronavirus threat, President Donald Trump on Wednesday threatened to withhold federal education aid if schools don't open, and then criticized new federal virus education guidelines.

"I disagree with @CDCgov on their very tough & expensive guidelines for opening schools," the President wrote on Twitter, as he labeled the plans 'very impractical.'

"I will be meeting with them!!!" Mr. Trump added, not the first time that he has differed with federal health experts on how to deal with the Coronavirus.

The 9 pages of CDC health guidelines for schools include a battery of suggestions for how best to deal with the virus in the new school year, including everything from developing plans for daily health checks of students and staff to recommendations on cleaning shared areas in schools.

"Identify who should wear cloth face coverings, and communicate the importance of wearing them," the CDC recommendations state.

The CDC suggestions clearly label the highest risk for students and staff as regular full-size classes and activities, with the lowest risk being online/virtual instruction.

Democrats said the President's public objections to the CDC education guidelines was regrettable.

"We should be listening to experts on how and when to reopen schools," said Rep. Gregory Meeks (D-NY). "Trump is telling Americans that preserving their health and safety is too 'tough & expensive.'"

The President's tweets came as New York City's Mayor announced that school would resume on a hybrid basis in September - with a combination of remote learning and regular school attendance - as kids would be at school no more than three days a week.