> The executive branch can't defund or "stop spending money on" anything. Nixon decided he just wouldn't spend money on programs he didn't like, and congress very rapidly passed a law that said that the president couldn't do it, because the "power of the purse" rests solely with congress.
That's all great in theory: in actual reality those laws are just words on paper, Congress has no interest in asserting its authority, and enforcement rests with the executive.