Alright, I'm going to throw out something that is going to seem very counter-intuative to solving the problem of overspending at the federal level.
Increase the pay of senators and representatives DRASTICALLY. We need some incentive other that getting bribed by cronies to run for the offices that control the government of the most powerful nation-state the world has ever seen.
I'm thinking in terms of 2 million/ year for House, 4 million/ year for Senate, and 10 million per yer for president (at least).
This will not solve the problem immediately, but it would hopefully encourage more qualified and not corrupt people to run for congress and/or president, as it would provide a generous living without needing to bend over for the various lobbies.