Mitt Romney's political ascension in 2012 is in many ways as remarkable as Barack Obama's in 2008, though with a crucial difference. Four years ago the rookie Illinois Senator managed to overthrow the Clinton machine because he better read his party's mood—namely, toward resurgent liberalism. Mr. Romney by contrast may become the 45th President despite often seeming out of sync with a new generation of center-right reformers.

Yet Mr. Romney's specialty during his business career was the turnaround, and gradually he applied...