Federal employee unions, Democratic members, and the White House strongly opposed a provision that would limit certain kinds of overtime pay for customs officers.
The provision prevents people from getting paid if they work for more than 40 hours a week. 
mnli hypothesis: The provision prevents people from getting paid if they work for more than 40 hours a week.  premise: Federal employee unions, Democratic members, and the White House strongly opposed a provision that would limit certain kinds of overtime pay for customs officers.