The federal government absolutely has the right and the duty to defend the nation’s borders, including any state border that happen to coincide. If Texas were letting in millions of future conservative voters, the federal government would be well within their rights to stop it.

What is happening right now is a total inversion. The federal government is facilitating invasion, a border state is attempting to stop it, and now the former is suing the latter to prevent a proper defense of the state/national border. They are literally applying the law backwards.