The solution does not lie in deciding between austerity or spending. The solution lies in what you do with money, rather than just spending more/less money compared to last year.
Cutting unproductive expenditure or increasing productive expenditure? Or some combination of both?
Given that the US has already shown the inability to spend its money wisely, does it seem prudent to try spending even more? What are you going to do differently with the money this time than you have done all these years?
The consequence of failure with increased spending is EPIC FAIL. While, the consequence of failure with austerity is epic fail. This is the reason cutting spending is seen as the slightly better way to deal with deficit.
Both methods dont guarantee success. Both methods have chances of success/failure.