[Robert DeLong]

On the basis of the Constitution and traditional legislative prerogatives, Congress lays claim to exclusive control over the purse. Nevertheless, while it is up to Congress to appropriate funds, it is also true that the President and the executive branch enjoy considerable discretion as to how those funds are spent. Existing studies tell us how the President formulates the budget and how Congress acts on the budget requests he submits. Surprisingly, we know relatively little about how the money, once appropriated, is actually spent. A notable exception in this field is a work by Lucius Wilmerding, Jr., published three decades ago.

Presidential Spending Discretion and Congressional Controls

Click on the second one down that has: {PDF} Spending Discretion and Congressional Control

It will download a PDF t your computer that is approximately 30 pages from a book. Haven't fully read the PDF but I am thinking it is up to the President to actually spend the money there or not.

There are also other links that look to be promising, also of PDF's, following the one mentioned above.

[Olog-hai]

I don’t buy that executive discretion canard especially when it excuses liberal spending. Faithful execution of the laws does not entail entertaining a chief executive’s whim, but within the bounds of law. Same goes for Congress in its appropriation of money.