Republican senators are requesting a formal investigation into the Biden administration's alleged coordination with the National School Boards Association (NSBA) and the National Education Association (NEA) and whether those relationships were used to silence parents critical of schools' COVID-19 and critical race theory policies.

Sen. Marco Rubio, R-Fla., authored the letter Tuesday with 10 GOP senators to the U.S. Department of Education Inspector General Sandra Bruce and U.S. Department of Justice Inspector General Michael E. Horowitz, urging them "to investigate the coordinated actions between the Biden Administration, NSBA, and NEA."

Sen Marco Rubio

Sen. Marco Rubio walks to the Senate subway after a vote in the U.S. Capitol on May 26, 2021. (Bill Clark/CQ-Roll Call Inc via Getty Images)

It was not immediately clear whether the inspectors general would take up the request. 

EDUCATION SECRETARY CARDONA SOLICITED NSBA LETTER COMPARING PROTESTING PARENTS TO DOMESTIC TERRORISTS: EMAIL

The request comes after Fox News Digital reported this month that Education Secretary Miguel Cardona solicited the much-criticized letter from the National School Boards Association (NSBA) to President Biden that compared protesting parents to domestic terrorists.

A Department of Education spokesperson previously denied that Cardona solicited the NSBA letter, despite an email indicating he did. 

President Biden's Department of Justice relied on the NSBA letter, which suggested using the Patriot Act against parents, in creating its own memo directing the FBI to mobilize in support of local education officials.

Fox News Digital also reported the National Education Association (NEA) sent a similar letter to social media companies, urging them to stifle "propaganda" about critical race theory that had supposedly stoked "a small but violent group of radicalized parents."

Critics have suggested that the NEA letter represents yet more coordination between government and interest groups to silence parents. This follows Cardona's solicitation of the NSBA letter and revelations that the White House coordinated with the NSBA for weeks before the group sent their original letter to President Biden.

Miguel Cardona is President Biden's secretary of education

Miguel Cardona speaks after President-Elect Joe Biden announced his nomination for education secretary on Dec. 23, 2020, in Wilmington, Delaware. (Joshua Roberts/Getty Images)

NEA URGED SOCIAL MEDIA GIANTS TO FIGHT ANTI-CRT 'PROPAGANDA' STOKING 'VIOLENT' 'RADICALIZED' PARENTS

"The Biden administration & the nation’s largest teachers union coordinated politically motivated attacks against concerned parents—all on the American taxpayer’s dime," Sen. Joni Ernst, R-Iowa, tweeted in announcing the request for an investigation.

The senators say parents deserve to know the truth. 

"While we remain concerned that parents who are peacefully protesting continue to be threatened by the failure of the Attorney General to rescind his memo, we are equally disturbed that the NSBA and NEA used taxpayer dollars – collected as dues from member schools – to carry out politically motivated attacks against concerned parents at the direction of the Biden Administration," the senators wrote. 

"These actions must be investigated as threatening and intimidating concerned parents should never be tolerated. Parents deserve to know the complete truth on this matter. Just because someone disagrees with you does not give you the right to silence them. "

critical race theory protest

Amy Carney speaks during a protest against critical race theory before a digital school board meeting at Coronado High School in Scottsdale, Arizona, on May 24, 2021. (Reuters)

Signing the letter were Rubio, Ernst, and GOP Sens. Roger Marshall of Kansas, Roger Wicker of Mississippi, Cynthia Lummis of Wyoming, John Barrasso of Wyoming, Mike Braun of Indiana, Jim Inhofe of Oklahoma, Steve Daines of Montana, Cindy Hyde-Smith of Mississippi and James Lankford of Oklahoma. 

Fox News' Tyler Olson and Peter Hasson contributed to this report.