Are presidential candidates running out of catchphrases?

President Barack Obama explained how the Unites States' global leadership would lead the world into an American century. He was speaking at the Air Force Academy Commencement in Colorado on Wednesday.

Presumed Republican candidate Mitt Romney also spoke of an American century in a foreign policy speech he made last October, when describing how the United States would lead the world.

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Excerpt of President Obama's commencement speech at the Air Force Academy's 2012 graduation Wednesday, transcript via The Wall Street Journal:

One of the reasons is that the United States has been, and will always be, the one indispensable nation in world affairs.  This is one of the many examples of why America is exceptional.   And it's why I firmly believe that if we rise to this moment in history, if we meet our responsibilities, then -- just like the 20th century -- the 21st will be another great American Century.  That's the future I see; that's the future you can build.

I see an American Century because we have the resilience to make it through these tough economic times.  We need to put America back to work by investing in the things that keep us competitive -- education and high-tech manufacturing; science and innovation.  We need to pay down our deficits, reform our tax code and keep reducing our dependence on foreign oil.  We need to get on with nation-building here at home.  And I know we can, because we're still the largest, most dynamic, most innovative economy in the world.  And no matter what challenges we may face, we wouldn't trade places with any other nation on Earth.

I see an American Century because you are part of the finest, most capable military the world has ever known.  No other nation even comes close.  Yes, as today's wars end, our military -- and our Air Force -- will be leaner.  But as Commander in Chief, I will not allow us to make the mistakes of the past.

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Excerpt from a foreign policy speech Romney made at the Citadel in South Carolina, transcript courtesy of the National Review.

Our next President will face many difficult and complex foreign policy decisions. Few will be black-and-white.

But I am here today to tell you that I am guided by one overwhelming conviction and passion: This century must be an American Century. In an American Century, America has the strongest economy and the strongest military in the world. In an American Century, America leads the free world and the free world leads the entire world.

God did not create this country to be a nation of followers. America is not destined to be one of several equally balanced global powers.  America must lead the world, or someone else will. Without American leadership, without clarity of American purpose and resolve, the world becomes a far more dangerous place, and liberty and prosperity would surely be among the first casualties.

Let me make this very clear. As President of the United States, I will devote myself to an American Century. And I will never, ever apologize for America.