Whoever places his hand on the Bible next January to be sworn in as president will take an oath to “preserve, protect and defend the Constitution” and provide for the common defense of our country. Keeping that oath will require a commitment to American leadership in an ever-changing world.

That is why all of today’s candidates — both the president and his Republican challengers — must articulate how they will maintain our nation’s security, prosperity, and values we hold so dear.

The brave men and women in our armed forces are second to none in the world, but providing for our common defense and re-igniting our engine of prosperity today requires more than just military might. We need a comprehensive foreign policy approach that includes not only defense, but also effective diplomacy and development assistance programs to ensure America’s protection, stability, and economic growth.

As the Republican presidential hopefuls crisscross Florida ahead of next week’s primary, they will address their plans to keep America at the top of its game on the global stage. Miami is recognized as the “Gateway to the Americas,” and we understand the challenges and opportunities that come with that title.

Right now trade supports one in five jobs here in Florida — a figure that has nearly doubled as a percentage of total jobs in the state in the past two decades. In 2010, Florida exported nearly $60 billion in merchandise to foreign markets. The future of our economic growth is in the international sector, and the fastest growing markets for U.S. goods and services are in the developing world. That’s why the small investment we make in our international affairs budget — just one percent of the total federal budget — acts as a jobs and revenue creator here at home.

People recognize the Sunshine State as one of the top tourist destinations in the world, bringing millions to the local economy. What Floridians may not know is that almost 30,000 international students study here each year through international exchanges. That intellectual capital brings about $800 million to the Florida economy. These students contribute to the vibrancy and diversity of our universities, colleges, and communities, while experiencing and learning why America is a truly great nation.

In addition to being good for business, our global programs are critical in protecting America and especially in preventing conflicts before they require military intervention. With our troops pulling out of Iraq and Afghanistan, we are going to need a strong corps of civilians on the ground to finish the job and win the peace. And as the Arab Awakening continues to unfold, we need our diplomats and experts there to ensure democracy has a chance to succeed and provide stability in that strategic region.

America has always stood on the side of liberty and served as a beacon of freedom and democracy for the rest of the world. Every day, we showcase the best of our values as we teach others how to grow food for themselves, develop good governance in their societies, and build their own economies. And we are also there in times of dire need — in the aftermath of a tsunami, hurricane or earthquake, in the ongoing battle to prevent the spread of HIV/AIDS, malaria, and other diseases that ravage developing countries, and in working to end the famine and poverty that far too often breeds instability.

It is always difficult to maintain our investments and commitments in times of economic difficulty and rising government debt. But from our respective times in Washington overseeing homeland security and the nation’s healthcare, we know that the alternative of stepping back from our leadership in the world is far worse. We cannot afford to isolate ourselves, letting others take our competitive edge in the global economy or by allowing our enemies to catch us with our guard down.

What we need in Washington today are individuals who recognize the importance of America’s leadership in the world, and we call on all of the candidates in 2012 to understand that it takes all of the tools available to us — diplomacy, development, and defense — to ensure America remains a leader for decades to come.

Tom Ridge is former governor of Pennsylvania and served as the nation’s first secretary of Homeland Security. Donna E. Shalala is the president of University of Miami and former Secretary of Health and Human Services. Both are advisors to the U.S. Global Leadership Coalition.