White House Chief of Staff Ron Klain defended teachers' unions who refuse to resume in-person teaching despite studies that have shown a low risk of spreading the coronavirus

Klain was asked Tuesday night why he believed so many public schools were still closed despite studies backed by the Centers for Disease Control and Prevention (CDC) that continued to show it is safe for K-12 schools to reopen.

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"I'll give you a word: money," Klain responded during a CNN interview. "That's why the president of the United States sent a plan to Congress even before he took office to make the investments you need to make the schools safe."

Klain later cited what he described as the "sizable grants" that schools in a CDC-touted study received. 

"President Biden has sent a plan to Congress that will make sure that the majority of our schools can be reopened in 100 days. ... Sadly, it costs money," Klain said. 

CNN anchor Erin Burnett pushed back, claiming transmission of the virus was "just not happening."

She then pointed to the Chicago Teachers Union, which recently voted to extend virtual learning.

"Ron, why do you think that the teachers unions in many cases are overruling what the studies show?" Burnett asked. 

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"I don't think that teachers' unions are overruling studies," Klain said. "I think that what you're seeing that schools haven't made the investments to keep the students safe. I mean, again, the Wisconsin study were classrooms of 12 on average. So that requires a lot more classrooms, a lot more teachers, or, you know, other kinds of arrangements to get them small, podding students very carefully."

"So we need to do the things to open safely. Most of the teachers I talk to, they want to be back in the classoom. They just want to know that it's safe and we as a country should make the investments to make it safe," Klain added.