GENEVA -- Secretary of State John Kerry was a man in his element in Sunday's predawn hours, when he announced details of a historic diplomatic agreement with Iran. Nearly all the roles he has played in a long career in public life came into view.
There was the pragmatic deal-cutting senator that Mr. Kerry was for nearly three decades -- the experience that most defines his approach to his new executive-branch job as chief diplomat.
The "i"-dotting lawyer was there, too, as was a little of the jaded war veteran and the ambitious politician who once sought but fell short of the presidency.
The agreement was the work of many lesser-known diplomats, including Wendy Sherman, the State Department's undersecretary for political affairs and its representative to the negotiations over Iran's nuclear program. But Mr. Kerry's admirers and critics both credit his tenacity and his game, give-it-a-shot style.
British Foreign Secretary William Hague praised Mr. Kerry's efforts Sunday, and the two joked about their mutual lack of sleep.
"I particularly want to pay tribute to the work of Secretary Kerry, who has been so determined throughout the negotiations with Iran to make sure that this is a robust deal, that everything that should be covered is covered and that every commitment that we wanted from Iran is as strong as it should be," Mr. Hague said in London. "And he has done that, and I really pay tribute to his persistence and his leadership in doing that."
Mr. Kerry flew overnight Friday to join the Iran talks that went into overtime Saturday. He went directly into back-to-back strategy sessions with foreign ministers of the other world powers trying to broker a deal, and also bargained directly with Iranian Foreign Minister Mohammad Javad Zarif.
"This is a partnership effort. No one country can do this," Mr. Kerry said in London later Sunday.
"The P5+1 were unified, and we all came together in consultation with a lot of effort together," he added, glossing over differences among the six-nation bargaining bloc that contributed to a breakdown in the Iran talks two weeks ago.
When the same fate appeared possible or likely Saturday evening, it was Mr. Kerry's stock that stood to fall furthest, because he had the most invested.
"From the outside, Kerry looks like he played the role of an effective closer," said Jon Alterman, director of the Middle East program at the Center for Strategic and International Studies.
Mr. Kerry has seemed relentless on any number of foreign policy crises in recent months. Alongside direct talks with Iran this fall, he bargained one on one with Russian Foreign Minister Sergei Lavrov and then with the U.N. Security Council to win a deal to destroy Syria's chemical weapons. He appeared unannounced in Kabul, Afghanistan, last month to try to salvage stalled security talks, and he kept up direct pressure on Israel and the Palestinians to continue peace talks he had invested months in starting.
That unyielding ambition has opened Mr. Kerry to criticism that he is attempting to resolve crises even where there is little chance of success. There is still no date for the oft-postponed peace conference that could end the Syrian civil war. In Afghanistan, weeks after Mr. Kerry reached a tentative agreement with President Hamid Karzai on a long-term security framework, Mr. Karzai is declining to sign it.
Still, more than other recent secretaries of state, Mr. Kerry is willing and apparently eager to intervene personally in crises and implacable problems, and to do it all at once. There is little of the caution that defined immediate predecessor Hillary Rodham Clinton or the reserve and formality of Condoleezza Rice.
He has confidence in his ability to lobby the U.S. case in person -- risky business if it goes wrong. Mr. Kerry often sounds like the foreign policy troubleshooter he was when, as a senator from Massachusetts, he was deployed by President Barack Obama to calm crises in Afghanistan and elsewhere.
Mr. Kerry "believes in personal diplomacy, believes that face-to-face negotiations are effective," State Department spokeswoman Jen Psaki said before Mr. Kerry joined the talks in progress Saturday. "I don't think he would mind hopping on the plane to fly to Geneva if that's a step that makes sense."