Quote from BeatingtheSP500:
The prez doesn't have the authority to spend a dime. Congress basically controls the $. It's a spurious correlation.
Quote from CollegeTrader33:
That is sort of true, sort of untrue. The President essentially can direct Congress where to spend the money, but they don't have to follow. Problem is, they usually do. Then the President can veto anything he doesn't like. To override the veto, you'd need an overwhelming majority in both houses, which usually never happens.
So, no he doesn't have a direct authority, but there is indirect authority.