If Donald Trump is currently wondering about the potential domestic political effects of a U.S. war in Iran, the answer is pretty clear: Don’t do it.
It’s certainly possible that Trump could benefit from a “rally around the flag” effect if war breaks out. But it’s by no means a sure thing. Political scientists have found that, as Richard Skinner put it: “Usually the rally-round-the-flag effect requires opposite-party elites to embrace the war (or at least not criticize it).” What’s important about that finding is what it doesn’t include. It turns out that whether a foreign crisis goes well or not isn’t really what determines the domestic political reaction. So for example George H.W. Bush got a huge bump in his approval rating when the Gulf War was won quickly and decisively – but so did Jimmy Carter when American hostages were taken in Tehran in 1979.