Executive Order 10988 - JFK. Authorized collective bargaining for government employees - opened a can of worms
https://en.wikipedia.org/wiki/Executive_Order_10988
And LBJ codified it into law thus allowing almost permanent FedGov unions. The federal government is 25.1% unionized. Total percent public employee credit unions is 33%-32%.
most executive orders can be killed from what i have read.