President Barack Obama has today nominated John Kerry to replace Hillary Clinton as secretary of state, calling the veteran US senator the "perfect choice" for America's top diplomat as he began reshaping his national security team for his second term.
Obama settled on Kerry, chairman of the Senate Foreign Relations Committee and the 2004 Democratic presidential candidate, after the frontrunner, UN Ambassador Susan Rice, withdrew from consideration last week.
Even as Obama put one important piece of his revamped Cabinet in place, he held off on naming a new defence secretary. The delay came in the face of a growing backlash from critics of former Republican Senator Chuck Hagel, who is considered a leading candidate to replace Leon Panetta at the Pentagon.
With Kerry standing at his side, Obama expressed confidence that the senator - a stalwart supporter who has long coveted the State Department job - would win swift confirmation from his Senate colleagues.
"As we turn the page on a decade of war, he understands that we've got to harness all elements of American power and ensure that they're working together," Obama said. "John's earned the respect and confidence of leaders around the world. He is not going to need a lot of on-the-job training."
The announcement fell short of the White House's earlier hopes of rolling out national security appointments, including a new CIA director, all at once before Christmas. That ambition was thwarted both by the Hagel controversy as well as other matters that have occupied Obama's attention - the standoff over the "fiscal cliff" and last week's Newtown gun massacre.
Kerry, 69, will take over take over from Clinton, who has been consistently rated as the most popular member of the president's cabinet.
But he will also have to pick up the pieces after a scathing official inquiry found serious security lapses by the State Department in the deadly September 11 attack on the US consulate in Benghazi, Libya - a report that has tarnished the final days of Clinton's tenure.
Kerry's nomination follows a political firestorm that engulfed Rice, seen as the early favourite for the State job, spearheaded by Republicans fiercely critical of her role in the administration's early explanations for the Benghazi assault.
Rice was defended by Obama, but said last Thursday (local time) she was withdrawing her name from consideration to avoid a potentially lengthy and disruptive confirmation process.
Kerry, known nationally for his presidential run and for his role as a Democratic power broker in the Senate, offers no such challenges.
His selection sets a pragmatic tone as Obama begins overhauling his national security team.
Kerry will be the leading Cabinet member charged with tackling a pressing global challenges, ranging from upheaval in the Middle East to Iran's nuclear standoff with the West and winding down the war in Afghanistan - all at a time of fiscal austerity at home.
WORKING RELATIONSHIP WITH OBAMA
Obama appeared subdued as he announced the nomination. He and Kerry had just returned from a funeral service for Senator Daniel Inouye at the National Cathedral.
Kerry looked on intently as Obama spoke, nodding occasionally. But the lawmaker known for sometimes long-winded speeches was not given a chance to address reporters at the White House. Clinton was absent due to illness but issued a statement saying Kerry would offer the "highest calibre leadership" at the State Department.
Kerry, a decorated Vietnam War veteran, has forged a close working relationship with Obama and gave him the keynote speech assignment at the 2004 Democratic convention that boosted the latter to the national stage and opened the way for his meteoric rise.
After losing narrowly to Republican George W Bush in the 2004 presidential election, Kerry forged a new identity as a congressional leader on foreign policy. He often served as a low-profile emissary and diplomatic troubleshooter for the Obama White House in places like Afghanistan, Pakistan and Syria.
But White House aides acknowledge that Kerry could be handicapped somewhat for lacking the close personal bond that Rice has with Obama.
On top of that, Kerry's departure from the Senate forces Democrats to defend his seat, where the party has only a slim majority. Just-defeated, but still-popular Massachusetts Republican Senator Scott Brown, who took office in early 2010 after winning the last special election for a Massachusetts seat, is widely expected to run.
The drumbeat of criticism against Hagel could prompt Obama to reconsider whether it would be worth the likely Senate confirmation battle if he were to chose him for the defence post.
But administration has given no sign of dropping Hagel from the short list and on Thursday joined allies rallying to support him against an onslaught over his record on Israel and Iran led by some pro-Israel groups and neo-conservatives, but also including some former colleagues on Capitol Hill.
It is the second time since Obama's re-election last month that the White House has found itself forced to defend a Cabinet candidate who has yet to be nominated for anything, a source of frustration for the president's advisers.
Also in the mix for the Pentagon job are Michele Flournoy, a former undersecretary of defence for policy, and Ashton Carter, the current deputy defence secretary.
The top candidates for CIA director, to replace David Petraeus who stepped down over an extramarital affair, are thought to be Michael Morell, currently acting CIA director, and John Brennan, a top counter-terrorism adviser to Obama and a former CIA official.