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As a freshman Senator in 1985, John Kerry was obsessed with the Philippines. Troubled by what he saw as America’s blind support of strongman Ferdinand Marcos, Kerry began introducing amendment after amendment calling for free and fair elections in the Philippines. Ronald Reagan reluctantly named Kerry to the delegation of election observers, and once there, Kerry choppered all over the country interviewing poll workers. What he found was troubling: evidence of massive fraud. He held a press conference and took his findings back to Reagan, who eventually dropped his support of Marcos and threw his weight behind Corazon Aquino, who was then declared the democratically elected leader of the country.

The episode won Kerry few friends , but was typical of the Massachusetts politician. Over the years, Kerry has hardly been Mr. Popularity in the clubby Senate, but his colleagues have begun to appreciate his stubborn smarts. When it looked like President Obama might name U.S. Ambassador to the United Nations Susan Rice to succeed Hillary Clinton as secretary of State, many protested – even those from the other side of the aisle. “[Kerry] would get a lot of support in the Senate because we all know John,” says Senator Lindsey Graham, a South Carolina Republican. “I often disagree with him on foreign and domestic policy, but he’s a collaborative guy by nature. I think he’s got a lot of experience. He knows most of the people on the world stage.”

In naming Kerry his nominee to his top cabinet post, Obama will get a nominee with a long and distinguished foreign policy record, a politician with experience and gravitas, but also one with very much his own mind. Whereas Rice got herself into trouble for sticking too closely to the talking points, from his perch as chairman of the Senate Foreign Relations Committee Kerry has often stretched Obama’s patience. Long before it was U.S. policy, Kerry called for the imposition of a no-fly zone in Libya, writing op-eds encouraging the Administration to follow suit. He also called for the U.S. to end its support for Egyptian President Hosni Mubarak well before the White House did. In an April 2011 speech at the Brookings’ Saban Center, he blasted the Administration for “wasting” time on “the wrong approach” on Middle East peace that was “unachievable.” That same month he criticized the Administration’s Pakistan policy as “not a real strategy” in an interview with USA Today’s editorial board. And in 2012 he held a hearing encouraging the Administration to arm Syrian opposition groups, a move the Administration is reportedly now weighing.

That’s not to say Kerry can’t also be a good foot solider. To some criticism he’s avoided holding gotcha oversight hearings. He played Mitt Romney in debate prep for the President during the campaign this year. In 2009 he flew to Afghanistan to persuade Afghan President Hamid Karzai to allow a runoff election instead of grabbing power in undemocratic fashion. He flew to Pakistan to negotiate the release of CIA operative Ray Davis. He also delivered the President’s messages to north and south Sudan before the referendum that split those countries and helped push through the stalled Strategic Arms Reduction Treaty in the 2011 lame duck session.

Indeed, Obama owes some of his political success to Kerry. On the day that Kerry won the 2004 Democratic nomination, he flew to Illinois for a fundraiser with Obama, then a Democratic nominee to represent Illinois in the Senate. Later that year, he also gave Obama the keynote spot in at the Democratic National Convention, a speech that launched Obama onto the national stage. And Kerry bucked pressure from his longtime friends, Bill and Hillary Clinton, to become one of the first sitting Senators to endorse Obama for President in 2007.

Both men enter Obama’s second term with an eye toward legacy, particularly in the foreign policy arena. And there’s much to tackle. Already Israel’s flare up in Gaza has brought the peace process back to the fore. Iran has hinted they might be ready for direct talks with the U.S., as Israel grows more nervous by the day at Tehran’s progress toward a nuclear weapon. Tens of thousands of protesters line the streets in Egypt. Syria stands at the brink with Bashar Assad’s finger on the chemical weapons’ trigger. Russia is getting impatient on missile defense, among other issues. As their economy struggles, Eurozone nations are still squabbling about banking integration and bailing out Greece. And there’s still the much-hyped and little-achieved pivot to Asia that Obama announced in his first term.

Barring a major surprise, Kerry will easily be confirmed and will presumably dig right into these issues. The question is, in building his legacy, will Kerry keep Obama’s in mind? He has, after all, been his own boss for almost his entire career. As Vice President Joe Biden – himself a longtime chairman of the Foreign Relations Committee — once wryly noted, subsuming one’s ambitions to another’s is no easy feat for a Senator. Kerry has proven that when his interests align with Obama’s, Obama has no greater ally on foreign policy. But will those interests always align? As with the Philippines, Kerry has a knack for publically forcing foreign policy changes; his challenge now will be to privately steer change from the inside.