What's the figure of speech used here?

But by insinuating himself successfully into the heart of the GOP, Rand Paul is doing more than mainstreaming libertarian-flavored foreign policy: He is forcing the purist, and therefore theoretical, instincts of his father's coalition to come into contact with the messy business of broad political persuasion. He will lose those along the way who prefer to lob rhetorical anti-imperial grenades from the margins. But he—and the country—stand to gain a whole lot more.