Let's say you are Mitt Romney. Your lead in New Hampshire seems to be shrinking. You decide to attack your closest rival in the state, Rudy Giuliani. You choose to go after . . . Giuliani's economic record. Um, doesn't that seem to be a tactical mistake? Doesn't Giuliani have much larger liabilities in a Republican primary, such as, among other things, his pro-choice views, his past support for gun control, and his continued support for some sort of reprieve for illegal immigrants who have jobs, identify themselves to the government, and have no criminal records? Why not go after any of those? I suppose you could answer that one should always attack one's opponent where he is strongest. And there's no doubt that Giuliani is running a campaign based on four things: his electability, his proven record, and his desire to continue to prosecute the war on Islamic terrorism and implement pro-growth economic policies. Exposing Giuliani's record as flawed could hurt him badly. But it also could be that he has a forceful response. That he has a case to make for a constitutionalist approach to the line-item veto. That he could turn the table. In which case, you may have picked the wrong fight.