In introducing Sen. John Kerry as his choice to succeed Hillary Clinton as secretary of state, President Obama noted last week that ďin a sense, Johnís entire life has prepared him for this role.Ē The Massachusetts Democrat will arrive at the State Department with vast knowledge and experience, having been part (again, borrowing the presidentís words) of ďevery major foreign policy debate for nearly 30 years.Ē

The challenge for the often insular Obama White House is whether it will take full advantage of the skills that Kerry will bring.

Clinton has been a strong secretary of state in many ways, traveling the world, through her political and diplomatic talents repairing the American image and enhancing the countryís influence. What she hasnít been permitted to do is take the lead, having a larger hand in shaping the agenda and decision-making overseas. Part of that involves the president wanting to keep control, and understandably so. Yet such an approach invites limits on what can be accomplished, a presidentís focus extending just so far.

Much of the case for selecting Susan Rice, the ambassador to the United Nations, for the position was the trust she has developed with the president and the vision they share. When Rice walked into a room, the thinking more likely would be: She truly has the presidentís confidence. James Baker had that kind of presence under George Bush the elder. As it is, the impressive Rice has shortcomings, real and spun, her undiplomatic and less persuasive ways, not the Republican outrage concerning her words about the attack in Benghazi.

The presidentís words frame the argument for letting Kerry lead. They are bolstered by what the senator has achieved for the president, for instance, as a diplomatic troubleshooter in Pakistan and Afghanistan, in gaining Senate ratification of the arms-reduction treaty with Russia.

Worth highlighting is the leading role he played in restoring relations with Vietnam. He did so with John McCain at his side, a reminder of how Kerry knows how to build consensus.

As chairman of the Senate Foreign Relations Committee, Kerry has traveled widely. He knows the players. He knows the dynamics of the crises, even more than Clinton did. The challenges are many, from the nuclear ambitions of Iran to accelerating climate change, from an assertive China to the old enmities and new uncertainties of the Middle East. The opening exists to see what a veteran hand can accomplish. How ambitious does the president want to be?