More immediately, the hawkishness now defining the early campaign could imperil the presidential hopes of Senator Rand Paul of Kentucky, the libertarian-leaning Republican who embraces a more restrained approach to American engagement with the world.

“The guy who’s now got the biggest challenge because of this is Rand Paul,” said Newt Gingrich, a former House speaker. “The Rand Paul worldview, which I suspect will change, is just incompatible with reality.”…

“He’s got, to some extent, to be an educator in this process,” said the expert, Richard R. Burt, a former ambassador and State Department official under President Reagan. “He needs to talk through with primary voters the kinds of questions that need to be asked before we commit U.S. forces abroad: How we can’t just have a visceral reaction. How does this impact American interests and security?”

But Mr. Paul’s detractors are not going to make that easy.