One interpretation of the evolving narrative of American power is that after periods of transformative upheaval brought about by crisis or confrontation, the system ultimately self-corrects to a more sustainable foreign policy bearing hallmarks of the liberal-internationalist worldview. Something similar happened after the revolutionary first terms of Ronald Reagan and George W. Bush, when the foreign-policy pendulum eventually swung back to more realist sensibilities during their second terms. In that view, the obvious foreign-policy continuity between the second Reagan term and the George H. W. Bush administration and between the second George W. Bush term and the Obama administration may represent a sort of sweet spot between the dynamic political tensions that shape America's role in the world.

Trying to explain American foreign policy by the various "schools" of foreign-policy thought is ultimately too simplistic, because modern American presidents have pursued a pretty consistent set of general principles you might call "pragmatic idealism," which is heavily guided both by American ideals but also by situational balances of power,

said Robert Kagan, the neoconservative intellectual and author whose book, The World America Made, has been lauded by both Romney and Obama. He goes on:

We will have predictable arguments between different foreign-policy camps that end predictably, but there is far more continuity to U.S. foreign policy than the candidates and experts like to acknowledge. That's why despite Obama's running as the polar opposite of President Bush, Obama's foreign policy looks more like the Bush administration's than almost anyone expected.

A more ominous interpretation of the current debate about American power would view the steady disappearance of traditional realists and liberal internationalists within the Republican Party as enduring. The realist/internationalist wing of the party may be fading with the passing of the Cold War generation of Republicans who championed it and as a result of the party's shift toward the South and Mountain West.

"In terms of the division between the neoconservative and realist wings of the Republican Party, I would argue that all of the intellectual energy is on the neoconservative side," Elliot Abrams, a deputy national-security adviser in the Bush 43 administration, told me in a comment echoed by other prominent Republicans. "It's hard to think of anyone below the age of forty who is pushing those ideas anymore. Where is the next generation of Republican realists?"

If the Republican Party moves so far to the right that liberal internationalists have no home other than with the Democrats, their brand of international engagement and moderation risks becoming just another political football tossed about in the partisan scrum of Washington politics. In that case, U.S. foreign policy will continue to vacillate wildly whenever power changes hands between the parties, the congressional opposition will keep stubbornly obstructing the president's foreign-policy initiatives out of a sense of duty and ideology, and the perceived erosion in the quality of U.S. global leadership will persist. Meanwhile, the ongoing quest for a bipartisan, post-Cold War consensus on America's rightful role in the world will remain quixotic. That's not a prescription for American exceptionalism but rather a narrative of continued American decline.

This article originally appeared at The National Interest, an Atlantic partner site. Follow @TheNatlInterest on Twitter.