The NEA represents 3 million teachers, support staff employees and other workers at public schools and colleges across the country. It is a major ally of the Democratic Party, and endorsed Biden’s reelection campaign in April, calling his the “most pro-public education and pro-union administration in modern history.”

The standoff broke into public view late last week when the White House said Biden would not be speaking in Philadelphia. Biden, who refers to himself as the most pro-union president in history, did not want to cross a picket line called by the staff union.