The opinions expressed are her own.

Conservative agitator Pat Buchanan’s new book says America might not survive until 2025; it’s called “The Suicide of a Superpower.” Even less alarmist observers are suddenly sounding a lot like Buchanan, as economists now predict that China may surpass the United States as the world’s largest economy a lot sooner than we thought, and important conferences are convened to deal with what Fareed Zakaria memorably dubbed “the post-American world.”

Over at Foreign Policy, my colleague Joshua Keating (coiner of the “Amerislump” phrase) has taken to tracking all the gloom-and-doom punditry under the heading “Decline Watch” on our website—and not a day goes by without a classic example, from the poverty-stricken new muppet on Sesame Street who doesn’t have enough to eat, to the supposed cocaine slump on Wall Street and the new government initiative to attract Chinese shoppers here — so they can buy Made in China goods, but at the cheap prices caused by our undervalued dollar.

The zeitgeist about America is so bleak that Secretary of State Hillary Clinton even begins her speeches these days being forced to remind audiences that the U.S. economy is still the world’s largest and its workers by far the most productive. Clinton, no declinist, invariably does her best to convince us that America is not retreating from the world at a time of national angst. Or at least that it should not.

“Beyond our borders,” she wrote in a recent piece for Foreign Policy that argued that the United States should make a strategic pivot away from the wars of the Middle East and toward the economic opportunities of Asia, many now question “America’s intentions — our willingness to remain engaged and to lead. In Asia, they ask whether we are really there to stay, whether we are likely to be distracted again by events elsewhere, whether we can make — and keep credible economic and strategic commitments, and whether we can back those commitments with action.”

Clinton’s answer is a resounding yes, but the questions themselves are revealing — even extraordinary — coming from a sitting Secretary of State, and the context is pretty clear: These are angst-ridden times to be an unabashed advocate of America’s role in the world, when everyone from Tea Partiers at home to financial markets abroad wonders about the staying power of this humbled superpower.

Sixteen years ago, when another sitting Secretary of State wrote for Foreign Policy, the world looked like a starkly different place to a top American official — a post-Cold War mix of opportunities and threats, bound together not so much by anything except the promise of American leadership. Indeed, said Warren Christopher, “the simple fact is that if we do not lead, no one else will.” It was an age, and one that now seems quaintly outdated, of America the indispensable nation.

Flash forward to today, when the United States struggles to assert its continued leadership in the world — or even its commitment to remaining there. Which makes it all the more depressing to listen to the early debates of the 2012 presidential campaign, where the rest of the world by and large doesn’t figure at all — except for the increasingly shrill protestations of some Republican candidates about their belief in America’s special destiny to lead the planet.

Consider Mitt Romney’s recent speech on foreign policy, before an audience of cadets at The Citadel, there to serve as an enthusiastic, uniform-clad backdrop while he questioned President Barack Obama’s patriotism. “God,” Romney lectured, “did not create this country to be a nation of followers.” Obama’s supposed sin? Not being sufficiently believing in the high church of American greatness, because, in 2009, he said, “I believe in American exceptionalism, just as I suspect the Brits believed in British exceptionalism and the Greeks believe in Greek exceptionalism.”

In the reductionist boilerplate of presidential politics, this has been translated into an alleged lack of faith in America. “I believe we are an exceptional country with a unique destiny and role in the world,” said Romney, the former Massachusetts governor who has enlisted a who’s who of Republican foreign policy heavyweights drawn heavily from the Bush administration to support his candidacy and casts himself as a classic GOP politician of the muscular internationalist type. “In Barack Obama’s profoundly mistaken view, there is nothing unique about the United States.”

Now, this might seem like a difficult charge to make stick against Barack Hussein Obama, the African-American son of a single mother who rose against all odds to become the nation’s first black president. But no matter: the more depressing point to me is simply that this is the debate Romney and others are determined to have, following in a long line of patriotic chest-thumping, rather than offering a real robust conversation over what to do for America at this time of troubles—or what sort of role America should play in the world.

But Romney’s problem is not just Obama and his multilateralist-loving, we’re-not-number-one-anymore-and-it’s-okay party, but many inside his own GOP. Americans in both parties, as surveys have consistently found, are simply fed up with bearing the costs of global security that come with being the world’s only superpower. Tell an audience that the United States currently spends more on defense than all the other countries in the world combined, and see what the reaction is. It’s no accident that the biggest applause lines at the GOP debates this year have been when candidates like Ron Paul and Jon Huntsman call for withdrawal from Afghanistan — as soon as possible.

But even if Americans can be convinced to keep bearing the costs — and that is very likely, given that this extraordinarily rich nation still spends just under 4 percent of GDP on defense and has had to make few sacrifices to maintain its military through a decade of post-9/11 wars in Afghanistan and Iraq — it’s still got a huge, and growing, image problem in a world where the decline narrative has set in. Recently, we asked a group of foreign writers and thinkers to play a game of Madlibs, and fill in the blank on this question: “The United States is…..” Here’s a sampling of what they said: “Not the promised land anymore.” “A sick superpower—but still a superpower.” “Facing a long spell of painful adjustments.” “Its own worst enemy because it refuses to recognize its most severe flaws and then address them.”

The last comment may be the most relevant of all. There’s much that ails America today, from schools that stink to collapsing infrastructure and a bloated financial system nowhere near finished dealing with the results of the burst housing bubble. But the bigger problem may be this: a political system that rewards bloviating over American greatness but not those whose hard work or big ideas might ensure Americans actually still have something to crow about.

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