It's easy for lawmakers to cut spending on someone else's priorities. The real test of fiscal discipline is the scrutiny they give their own. For Republicans, that means the Defense Department—by far the largest federal program funded through annual appropriations. We don't believe the continuing resolution is the right place to be making deep cuts in federal spending, but we do think Congress has to start the process of closing the budget gap this year. And it has no chance of succeeding unless lawmakers go to where the big money is: defense, entitlements and tax breaks.