We know what works. History has taught us, or would, if we paid attention to its lessons.
Republican presidential candidates should be talking about what they will not do and then speak of plans to clear a better path to success for those who would get up and walk it. Tell people to stop waiting for the government bus that will drop them off where they started with little to show for the journey; build wealth, don't steal it from others; eliminate unnecessary regulations; reform the tax code so that everyone contributes something to America because we all benefit from freedom; learn again to live within our means and stop envying others. All these are good for starters.
They should also promise, if elected, to require every agency and program to justify its existence. If any work currently being done by government can be done better and at less cost by the private sector, it should. If any are outdated, inefficient or unnecessary, they should be ended and the money saved applied to our crushing debt.
Most of all, Republican presidential candidates should tell Americans they can't save us. Only we can save ourselves, at least in the secular sense. The Founders gave us a great document -- the Constitution. Now the question is, to paraphrase Ben Franklin, can we keep it? You people aren't messiahs, anymore than President Obama, but you might be apostles of the Constitution.