The largest federal employees union is suing the Homeland Security Department to stop the Trump administration from canceling its contract with T.S.A. workers.

The largest federal employee union filed a lawsuit on Thursday seeking to block President Donald Trump's administration from ending collective bargaining for nearly 50,000 Transportation Security Administration officers that staff checkpoints at U.

The American Federation of Government Employees accused the Trump administration of retaliating against the labor group over their efforts to block the mass firing of probationary workers across government.